192 NATURAL SCIENCE [September 



Newton's figures of the skull of the allied genus Sccqthognathus 

 (Phil. Trans. 1888, B. pi. 77 and 78). There appears to be 

 no palaeontological evidence to warrant the great length which 

 Owen gave to the hindermost ribs in his restoration, and these 

 have, therefore, been considerably shortened, so that the contour 

 of the ventral abdominal wall now passes evenly from the ribs 

 to the ischial bones of the pelvis. So little is yet known con- 

 cerning the coracoids and sternum of Ornithosauria that, beyond 

 representing the sternum as keeled and as articulating with the 

 first few ribs, but little has here been attempted. 



Of the four restorations which form the subject of the present 

 article the greatest interest probably centres around that of 

 Ichthyosaurus, inasmuch as the recent additions to our knowledge 

 of this genus have rendered possible a very complete restoration. 

 The species chosen is Ichthyosaurus communis from the Lower Lias 

 of Lyme Regis, and the specimens which form the basis of the 

 reconstruction are those in the Geological Gallery bearing the 

 register numbers (41849) and (2000,1*). This is the same 

 species as that of the well-known restoration of Owen's (" Anat. of 

 Vert.," vol. i., 1866, p. 170). An illustrated summary of recent 

 papers on the Ichthyopterygia has already appeared in the pages of 

 this journal (Lydekker, Nat. Sci., vol. i., 1892, pp. 514-521), and 

 in this article is reproduced Fraas's figure of the wonderfully well- 

 preserved specimen of Ichthyosaurus quaclriscissus, showing the 

 complete outline of the body and affording incontrovertible evidence 

 of the presence of a bilobed tail with the vertebral column running 

 down the ventral lobe, and the existence of a series of irregular 

 integumentary fins along the back (Fraas, Ncues Jahrb. f. Mineral., 

 1892, Bd. 2, pp. 87-90). These details are reproduced in the 

 present restoration (Fig. 2), and, while the proportionate size and 

 the details of the paddle skeleton are taken from the specimens of 

 Ichthyosaurus communis above specified, the postaxial flap of the 

 paddle, not supported by skeletal parts, is added from Fraas's figure, 

 from the museum specimen of Ichthyosaurus intermedins (R. 1664), 

 described and figured by Lydekker (Gcol. Mag., dec. 3, vol. vi.,*1889, 

 pp. 388-390), and from Owen's figure of the paddle of Ichthyosaurus 

 communis (?) (" Liassic Reptilia," part hi., 1881, pi. 28, fig. 5). The 

 outline and details of the skull were introduced mainly from speci- 

 mens (39492) and (R. 1164) of Ichthyosaurus communis, both of 

 which exhibit a very complete side view of the skull. In none of 

 the specimens of Ichthyosaurus communis at the Natural History 

 Museum are the bones of the pectoral girdle undisturbed, so that in 

 restoring this part of the skeleton the shapes of the constituent 

 bones were taken from specimen (41848), but their mutual relations 

 from the very complete girdle which the museum possesses of 



