TWO NEW ELASMOBRANCH FISHES. 235 



the tail ; hut the parts of the paired fins are scattered, and only 

 fragments remain. The specimen, however, is of special impor- 

 ta,nce, because displaced portions of both jaws with groups of the 

 teeth are also preserved. The characteristic large anterior fon- 

 tanelle in the cranium is well displayed as in the type specimen. 

 The teeth (fig. 3) are relatively small and closely arranged, several 

 series evidently functional at one time. Their exact shape is 

 difficult to determine, but they seem to be transversely elongated 

 rhomboids, with a, low crown, which is siTiooth, compressed antero- 

 posteriorly to a sharp edge, and sometimes rising in the middle to 

 a little cusp. Many of the vertebra,l centra clearly exhibit the 

 secondary calcification round the primary double-cone. A frag- 

 ment of a pelvic fin seems to denote a male individual, and a row 

 of slightly enlarged, pointed shagreen-granules nnay have belonged 

 to the clasper. The two dorsal fin-spines (fig. 3a, d}, cF), though 

 fractured, are shown to be nearly similar in size and shape, and 

 their length equals about one-quarter of the distance between 

 their insertions. The spine of the first dorsal is supported not 

 only by a short triangular cartilage behind, but also by a larger 

 and more extended cartilage in front. Traces of the fine stellate 

 shagreen are seen on the rostrum. 



Affinities. — The new genus and species now described evidently 

 represent a family closely related to the Spinacidre, but still re- 

 taining the anal Hn and a less specialised dentition. Protospinax 

 is indeed a generalised type such as might be expected among 

 Jurassic E^asmobranchs when the Batoids were beginning to be 

 differentiated. The Batoids themselves were first represented by 

 the Rhinobatidfe. and it is interesting to notice that one member 

 of this family (Belemnohatis) v.oi\te.Tsi\>oYi\.Yj with Protospinax had 

 a spine in front of eacli of its two dorsal fins. 



EXPLANATION OF PLATE L 



Fig. 1. Cros.^orliinns Juraasicvs, sp. 'n. ; nearly complt'te fish, nat. size. — Litho- 

 graphic Stone; EichstSdt, Bavaria. I, 11,111. the three paired dermal 

 lappets. . [British Museum no. P. 11211.] 



2. Protospinax annectans, gen. et sp. n. ; fragmentary fish, ono-sixtli nat. 



size. — Ibid. a. anal fiu ; d^. spine of first dorsal fin. [British Museum 

 no. P. 8775.] 

 2a. Ditto ; portion of lateral line of same specimen enlarged four times to show 

 supporting ringlets. 



3. Ditto ; group of teeth enlarged ten times. — -Ibid. [British Museum 



no. 37014.] 

 3a. Ditto; portion of tail pf same specimen, showing dorsal fin-spines ((V-, d~), 

 nat. size. 



