DUSSUMIERIID,E-^-LYGISMA 33 



a sharp projecting knob at its insertion, its length about half head; side 

 of the mandible apparently with broad-based, uniform, rounded, sharp- 

 edged teeth, rather low and apparently incisor-like, eight to ten in num- 

 ber ; no canines (it is possible that these teeth are misinterpreted) ; opercles 

 well developed, snout short and blunt. Eye large, the orbit crossed by a 

 narrow depression (a bony interorbital shelf). Fin rays not to be ac- 

 curately counted; dorsal small, with about twelve rays, nearly midway 

 between occiput and base of caudal; ventrals short but with numerous 

 rays, nearly half length of mandible, inserted a shade in advance of 

 front of dorsal. Anal partly obliterated, with perhaps seven rays trace- 

 able; no trace of adipose fin, caudal fin crushed, apparently large and 

 forked. No certain trace of scales on body, one loose scale large, nearly 

 circular, its edges indistinct. About twenty vertebrae shown behind front 

 of ventral fin, nearly as many before it being obliterated. Vertebrae 

 deeper than long, with weak spines ; no ribs preserved ; hypural oblit- 

 erated. 



This form apparently belongs to the ISOSPONDYLI, but it seems to fit 

 into no existing genus. The dentition, if correctly interpreted, is unique 

 in the group. We leave this genus with QU^SITA provisionally among 

 the DUSSUMIERIID.E. 



(The name is from ddX6ei<;, not stormy, that is, living in a sea free 

 from dXo<;, muddy foam.) 



29. Lygisma tenax Jordan and Gilbert, new genus and species. 

 (Plate VIII, fig. 2; Plate XIV, fig. 1) 



Type (No. XVI) 3y inches in length, from the Hadley collection at 

 El Modena. It shows the head from above with the vertebral column and 

 the long, strong caudal fin complete. The other fins are scarcely indicated. 

 Head large, broad, about five in length, a little longer than caudal fin ; ver- 

 tebrae about forty-three, well ossified and hourglass-shaped, the column 

 holding firmly together; eyes very large, longer than the bluntish snout 

 and broader than the concave interorbital space; post-temporal bones 

 present ; no spines on head ; caudal strong, well forked, the lobes nearly 

 as long as head. No trace of other fins preserved. In the example before 

 us the vertebral column fully intact is much distorted and twisted in a 

 fashion almost comical. The neural spines seem weak. Hypural strong, 

 but ill-defined. 



A second example (No. CVII) shows the same species from a differ- 

 ent angle. The large head, seemingly three and a half in length, is badly 

 crushed, but indicates a conical form, with large eyes, and apparently 

 short, oblique mouth; the depth is not far from five in length; pectoral 

 inserted low, the fin split, about 6 rays in each half; ventrals long, both 



