LIASSIC ICHTHYOSAURS. 83 



minuteness of the teeth of Ich. hngirostris we may discern the transitional step to the 

 edentulous Ichthyosaurs described by Prof. Marsh.^ 



I conclude that the present, together with other long- and slender-jawed Fish-lizards, 

 may have preyed in a great degree upon the contemporary Cephalopods with internal 

 rudimental shells as well as on Fishes. The eye in Ich. longirostris is proportionately 

 large, like the orbit which the sclerotic circle almost occupies, suggestive of the nocturnal 

 habits of the species ; the plates seem to have been not fewer than sixteen in number. 

 The present s|)ecies, like Ich. tenuirostris, is characterised by the large size of the 

 pectoral fin, and that of the ossicles representing the carpals and phalanges of its digits. 

 These, however, are limited in number, as in Ich. tenuirostris; the three normal digits (ii, 

 III, iv) are instructively conserved, though not terminally entire, in fig. 7, Tab. XXVIII. 

 The supplementary ossicles here preserved are, situated as in the tenuirostral species, 

 along the ulnar margin, forming a sort of rudiment of the digit (v), which is normally 

 developed in Ich. communis and Ich. intermedins. 



The scapula, clavicle, and coracoid of the same side as the fin are definite, but 

 dislocated. The coracoid repeats the type of that of Ich. tenuirostris so far as having 

 the anterior notch the best marked, but the posterior one is more faintly indicated. 

 The anterior notch (Tab. XXVIII, fig. 9) is placed further back, and becomes lateral 

 rather than anterior. The articular prominence is also nearer the hind border of the 

 lamelliform bone. 



The radius and radio-carpal bone are notched anteriorly, as in Ich. tenuirostris. 



The pelvic paddle has the same relative size as in that species, and the same 

 tridactyle structure. 



I reckon forty-eight vertebrae between the skull and pelvis ; fifty-two vertebrae can 

 be made out in the extent of the caudal region preserved ; to which may be added about 

 a score more for the wanting pinnigerous terminal portion of the tail, which probably 

 has been torn off" by predatory assailants of the dead reptile. 



Besides the Liassic locality of Barrow-on-Soar, specimens and parts of Ichthyosaurus 

 longirostris occur in the zone characterised by ulSgoceras angulutum ; also in the zone of 

 Arietites Bucklandi? 



I. Ichthyosaurus latimanus, Ow.^ Tab. XXIX, figs. 2, 7. 



This species is nearly allied to Ich. communis in the size and construction of the 



1 " A New Order of Extinct Reptiles (Sauranodonta)," ' Amer. Journ. of Science and Arts,' vol. xvii, 

 Jan., 1879, p. 85. 



2 See the classical Monograph, by Dr. Wright, F.R.S., &c., in the volumes of thePalseontographical 

 Society issued in 1878 and 1879. 



3 'Report,' ut supra (1839), p. 123. 



