262 SATTKOPTERYGIA. 



earliest, has been rejected on account of its uncouthness l . The 

 name P. etheridgei was applied to a small skeleton differing from 

 the type in having 30, in place of 31, cervical vertebra?, and in 

 some other slight details ; since, however, an instance has been 

 published of a variation in the number of presacral vertebrae among 

 the Crocodilia 2 , it appears highly probable that a similar variation 

 would occur still more frequently in the present order, where there 

 is great specific variation in the number of the cervical vertebrae. 

 The specimen, No 48001, mentioned on p. 238, indicates, moreover, 

 either the incipient division of a single cervical centrum into two, 

 or the imperfect coalescence of two distinct centra. 



While P. dolicliodirus appears to have been the commoner form 

 at Lyme-Eegis, the present species seems to be more abundant at 

 Street. 



Hab. Europe (England). 



2018*. Slab showing the ventral aspect of a nearly entire immature 

 {Fig.) skeleton ; from the Lower Lias of Street, near Glaston- 

 bury, Somersetshire. The type specimen. Eigured by 

 Hawkins in his ' Memoirs on Ichthyosauri, &c. ' and 

 ' Sea Dragons,' pi. xxiv., as P. triotarsostinus ; by Buck- 

 land in his ' Geology and Mineralogy ' (Bridgewater 

 Treatise), pi. xvii., as P. dolicliodirus ; and by Haughton 

 in his 'Manual of Geology,' fig. 40, under the latter name. 

 Noticed by Huxley in the ' Quart. Journ. Geol. Soc.' 

 vol. xiv. p. 284. The distal portion of the left pectoral 

 limb is wanting, and the tarsus of both sides is imperfect. 

 In the pectoral girdle the omosternum is damaged, and the 

 caudal part of the vertebral column has been displaced. 



Haivkins Collection. Purchased, 1834. 



2019*. Cast of the preceding specimen, with the left pectoral limb 

 restored. Haivkins Collection. 



2020* (14551). Slab showing the ventral aspect of the nearly entire 

 (Fig.) skeleton of an immature individual ; from Street. Eigured 

 by Hawkins, op. cit. pi. xxvii., and noticed by Huxley, 

 op. cit. p. 284 (as No. 14541). The distal portion 

 of the left pectoral limb is wanting, and both the pectoral 

 and pelvic girdles are imperfect. The displacement 

 of the cervical ribs exhibits very clearly the double costal 

 facets. The upper costal facets throughout the series 



1 In the ' Rep. Brit. Assoc' for 1839, Owen proposed to reject this name as 

 being incorrect. 



2 Baur, Zool. Anz. vol. ix. p. 689 (1886), records 25 in place of the normal 24 

 presacral vertebrae in Garialis gangeticus. 



