72 BRITISH FOSSIL REPTILES. 



frontal suture. The maxillary is separated from the external nostril by a junction of the 

 premaxillary with the lacrymal. 



The sclerotic plates are often from fifteen to seventeen in number. 



The surangular is deeper, and forms a larger proportion of the outer surface of the 

 hind half of the mandibular ramus than the angular. It terminates or disappears at the 

 usual point between the deutary and spleuial, in advance of the angular ; it develops on 

 its upper border a small but well-marked corouoid angle bounding anteriorly the con- 

 cavity under the hind part of the orbit. Beneath this angle or process begins the neuro- 

 vascular groove, which extends, gradually shallowing, a short way forward. The splenial 

 element begins to show at the lower margin of the ramus about the mid-length of the 

 angular; it unites with its fellow to form the hinder two thirds of tbe symphysis mandi- 

 bulae (Tab. XXVI, fig. 2, 32'). The articular piece is brought into view by its partial 

 dislocation backward in the right ramus of the subject of fig. 1, Tab. XXVI. 



The stem of the episternum equals in length one half of the cross-bar; in receding 

 therefrom it slightly expands and becomes flattened. In one young specimen a median 

 cleft extended a short way forward from the end. 



The clavicles are distinct, long, and less strong than in Ich. communis, feebly bent, 

 with the concavity behind and within, gradually narrowing to each end, and having a 

 sutural surface beneath and behind, some way along each end ; the shorter one engrains 

 with the episternal cross-bar, the longer one with the fore part of the scapula. Of this 

 bone the fore border is straight, the hind one concave through the backward production 

 of the humeral joint ; near this the outer surface is shghtly excavated. In the coracoid 

 the humero-scapular articulation is of less relative extent than in IcMliyosaurus communis. 

 The anterior notch is broader, but is as deep as the hinder one ; the intervening tract, or 

 neck, is relatively larger than in Icli. platyodon or Iclb. tenuirostris. 



The present species has afforded some ground of the restoration outlined in fig. 1, 

 Tab. XXIX. The humerus is marked 53 ; the radius 54 ; the ulna 55. The fore 

 border of the radius is entire, not notched. The antibrachium supports, as usual, three 

 ossicles (56), followed by four rather smaller (56')- Regarding these as carpals, they 

 support four metacarpal ossicles (57—57'), from which are continued five longitudinal 

 series of progressively diminishing phalanges. The anterior or radial metacarpal (57') 

 supports two digits, of which the radial may be symbolised as I, the next series as 

 digit 11. The three other series. III, IV, V, are supported by their respective meta- 

 carpals. Each digit consists of numerous phalanges, progressively decreasing to the end. 

 A series of small supplementary ossicles is applied to the radial border of digit I, and to 

 the ulnar border of the digit V, so that seven ossicles may be counted in the same 

 transverse line along the middle third or fourth of the series. The number of phalanges 

 is, however, less than in Ich. communis, and the fin is relatively narrower. The characters 

 of the fore paddle above defined are well shown in specimens from the Lias of Lyme 

 Regis and of Street, in the British Museum. 



