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OP

 FIVE 
 GENERA 
 OF 
 MESOZOIC 
 REPTILES. 
 55 
 

saurus

 Crarriptoni 
 of 
 the 
 Upper 
 Lias, 
 which 
 Prof. 
 Seeley 
 has 
 made 
 

the

 type 
 of 
 the 
 genus 
 Bliomaleosaurus, 
 and 
 which 
 is 
 characterized 
 

by

 its 
 enormous 
 head 
 and 
 teeth, 
 short 
 mandibular 
 symphysis, 
 and 
 

short

 neck, 
 in 
 which 
 the 
 vertebrae 
 are 
 comparatively 
 few 
 in 
 number, 
 

with

 short 
 centra, 
 having 
 deeply 
 cupped 
 faces, 
 and 
 carrying 
 double 
 

costal

 facets, 
 and 
 with 
 firm 
 articulation 
 of 
 the 
 arches. 
 The 
 pecto- 
 

ral

 girdle 
 is 
 unknown 
 in 
 this 
 form 
 ; 
 but 
 in 
 the 
 Lower 
 Liassic 
 Plesio- 
 

saurus

 megacephalus, 
 as 
 well 
 as 
 in 
 the 
 closely 
 allied 
 P. 
 arcuatus 
 of 
 

Owen,

 in 
 which 
 the 
 head 
 and 
 neck 
 exhibit 
 all 
 the 
 generic 
 characters 
 

of

 the 
 so-called 
 Bliomaleosaurus, 
 this 
 part 
 of 
 the 
 skeleton 
 is 
 shown. 
 

It

 has 
 an 
 extremely 
 large 
 omosternum, 
 forming 
 a 
 shield-like 
 plate, 
 

with

 a 
 long 
 wide 
 notch 
 on 
 the 
 anterior 
 border, 
 and 
 apparently 
 

consisting

 of 
 a 
 single 
 element 
 ; 
 the 
 scapulas 
 and 
 coracoids 
 being 
 of 
 

the

 general 
 type 
 of 
 those 
 of 
 Plesiosaurus. 
 Mention 
 has 
 already 
 been 
 

made

 of 
 the 
 large 
 Sauropterygian 
 founded 
 upon 
 vertebras 
 and 
 teeth 
 

from

 the 
 Great 
 Oolite, 
 to 
 which 
 the 
 name 
 Thaumatosaurus 
 oolithicus 
 

has

 been 
 applied 
 ; 
 and 
 a 
 comparison 
 of 
 the 
 figures 
 of 
 these 
 speci- 
 

mens

 with 
 Plesiosaurus 
 Cramptoni 
 fails 
 to 
 show 
 even 
 a 
 specific 
 dis- 
 

tinction

 between 
 the 
 two, 
 although 
 this 
 might 
 be 
 indicated 
 if 
 fuller 
 

materials

 were 
 available. 
 Since, 
 therefore, 
 I 
 fail 
 to 
 see 
 any 
 charac- 
 

ters

 by 
 which 
 Bliomaleosaurus 
 can 
 be 
 distinguished 
 from 
 Thauma- 
 

tosaurus,

 I 
 can 
 but 
 include 
 the 
 former 
 in 
 the 
 latter 
 genus. 
 The 
 

cervical

 vertebrae 
 of 
 Thaumatosaurus, 
 although 
 they 
 agree 
 with 
 

those

 of 
 the 
 present 
 form 
 in 
 their 
 short 
 centra 
 and 
 double 
 costal 
 

facets,

 are 
 distinguished 
 by 
 their 
 deeply 
 cupped, 
 in 
 place 
 of 
 nearly 
 

flat,

 terminal 
 facets, 
 and 
 are 
 thereby 
 also 
 distinguished 
 from 
 

those

 of 
 Pliosaurus. 
 Vertebrae 
 of 
 the 
 type 
 of 
 those 
 of 
 Thaumato- 
 

saurus

 occur 
 from 
 the 
 Lias 
 to 
 the 
 Kimeridge 
 Clay, 
 the 
 species 
 

of

 the 
 latter 
 horizon 
 having 
 been 
 long 
 ago 
 described 
 by 
 Cuvier 
 

as

 Plesiosaurus 
 carinatus. 
 With 
 regard 
 to 
 the 
 generic 
 position 
 

of

 the 
 species 
 forming 
 the 
 subject 
 of 
 this 
 communication, 
 I 
 may 
 

observe

 that 
 before 
 I 
 had 
 satisfied 
 myself 
 as 
 to 
 the 
 difference 
 of 
 

its

 cervical 
 vertebrae 
 from 
 those 
 of 
 Thaumatosaurus, 
 and 
 also 
 as 
 

to

 the 
 nature 
 of 
 the 
 pectoral 
 girdle 
 of 
 any 
 of 
 the 
 species 
 which 
 I 
 

include

 in 
 the 
 latter, 
 I 
 considered 
 * 
 that 
 the 
 species 
 in 
 question 
 

might

 enter 
 that 
 genus, 
 since 
 I 
 did 
 not 
 regard 
 the 
 elongated 
 man- 
 

dibular

 symphysis 
 as 
 necessarily 
 indicative 
 of 
 generic 
 distinction. 
 

The

 pectoral 
 girdle 
 of 
 P. 
 arcuatus 
 is, 
 however, 
 so 
 totally 
 different 
 

from

 that 
 of 
 the 
 Oxfordian 
 form 
 that 
 I 
 can 
 no 
 longer 
 maintain 
 this 
 

view;

 especially 
 with 
 the 
 concomitant 
 difference 
 in 
 the 
 cervical 
 

vertebrae.

 I 
 cannot, 
 moreover, 
 very 
 well 
 include 
 the 
 present 
 form 
 

in

 Pliosaurus, 
 from 
 which 
 it 
 is 
 distinguished 
 by 
 the 
 firm 
 articulation 
 

of

 the 
 arches 
 with 
 the 
 centra 
 of 
 the 
 vertebrae, 
 and 
 the 
 longer 
 epipo- 
 

dial

 bones 
 ; 
 and 
 I 
 therefore 
 — 
 much 
 as 
 I 
 dislike 
 proposing 
 new 
 

generic

 terms 
 — 
 feel 
 bound 
 to 
 refer 
 it 
 to 
 a 
 new 
 genus, 
 for 
 which 
 I 
 

think

 the 
 name 
 Peloneustes 
 will 
 be 
 appropriate. 
 The 
 Kimeridgian 
 

vertebra

 to 
 which 
 Professor 
 Seeley 
 has 
 applied 
 the 
 name 
 Plesiosaurus 
 

sterrodirus

 will 
 belong 
 to 
 the 
 same 
 genus, 
 and 
 also 
 the 
 femur 
 

described

 by 
 Phillips 
 as 
 P. 
 cequalis. 
 

 Geol. 
 Mag. 
 decade 
 iii. 
 vol. 
 v. 
 p. 
 353