4 



BKITISH FOSSILS. 



Locality. — These specimens were found in the same block of 

 Gotham marble at Aust as those described in the preceding memoir, 



Plate VII. Fig. 9—12. 



LEGNONOTUS. Gen. Nov. 



[Genus LEGNONOTUS {Myvov, a fringe, vutos, the back). Egerton. (Sub-kingdom 

 Vertebrata. Class Pisces. Order Goniolepidoti. Family Lepidostei. Sub-family 

 Lepidostei homocerci.) Dorsal fin extending from the nape to the tail ; teeth conical.] 



Legnonotus Cothamensis. Sp. Nov. 



Description, — The same block of Gotham marble which con- 

 tained the two preceding species, yielded also the curious little fish 

 represented in the accompanying plate (fig. 9.), of twice the natural 

 size. The head and detached jaw, of which enlarged views are 

 given at figs. 10. and 11., probably belonged to the same species, 

 at all events they differ entirely from the characters of Pholido- 

 phoriis, the only other genus associated with them. It is not 

 without some hesitation that I have ventured on the slender evi- 

 dence aff'orded by a mutilated specimen, and a few fragments to 

 establish a new genus ; and I should not have done so, could I by 

 any licence of interpretation of the characters of genera already 

 acknowledged have referred this fish to any one of them. The 

 dorsal fin is a feature of such paramount importance, that it cannot 

 be disregarded ; and the peculiarities of this organ in the subject 

 before us, are quite irreconcileable with any genus hitherto dis- 

 covered. It commences immediately behind the nape and extends 

 nearly to the tail, and contains about 30 rays all supported on 

 strong perpendicular interapophyses. Six or seven of the anterior 

 rays are single spines, rather arched and shorter then the succeed- 

 ing rays. The latter are thicker than the anterior ones, and 

 although single for some distance from the body, are subdivided 

 at their extremities and traversed by transverse articulations at 

 rather distant intervals. The nearest approach to this construction 

 of the dorsal fin is found in the Sauroid genus Macrosemius, but in 

 other respects Legnonotus resembles a Pholidophorus, or still more 

 nearly the genus Notagogus. The former has a small single fin on 

 centre of the back, the latter has a double dorsal fin ; features quite 

 sufficient to distinguish them from the subject before us. The fish 

 measures IJ inch from the insertion of the pectoral fin to the base 

 of the tail, and of an inch in depth. The dorsal fin occupies an 

 inch of the back, and the anal fin is nearly an inch distant from 



