COCHLIODONTIDZR. 
169 
present in the mandible. Teeth with broad, backwardly-extended 
bases, overlapping; crown consisting of three slender, curved, sub- 
conical cusps, separated by a pair of rudimentary denticles. Noto¬ 
chord mainly persistent, in part replaced by feeble cyclospondylic 
vertebral centra. 
A nearly complete description of the type specimen (female) of the 
single known living species, C. anguineus , from Japanese seas, is 
given by S. Garman in the Bull. Museum Comp. Zoology, Harvard 
College, vol. xii. no. i. (1885). Further notes, and a large figure, 
are published by A. Gunther, Hep. Deep-Sea Fishes (‘ Challenger ’ 
Reports, vol. xxii. 1887, p. 2, pi. lxiv.). 
Only one fossil species has hitherto been recorded, and this n 
o£ det^che^^e^h:—^^ 
? lawleyi , J. W. Davis, Proc. Zool. Soc. 1887, 
p. 542 ; incertce sedis , It. Lawley, Nuovi Studi sopra ai 
Pesci, etc., delle Colline Toscane, 1876, p. 87, pi. i. fig. 1. 
—Pliocene ; Tuscany. 
erely 
Division B .—Two dorsal fins present; (fill-clefts 
five in number . dry cjj. 
Family COCHLIODONTIDiE. 
An imperfectly ‘definable family, apparently related to the Cestra- 
ciontidae, but with a more specialized dentition. At least one of 
the transverse series of teeth encircling each ramus of the jaw is 
fused into a continuous curved plate, sometimes with an even coronal 
surface, sometimes with ridges and furrows marking the boundaries 
of its components ; this plate increasiug in size by additions to its 
inner margin, and the outer border gradually coiling inwards instead 
of becoming detached. The root and the crown are approximately 
of corresponding thickness, the attached surface of the former 
being thus almost parallel to the coronal contour. Coronal surface 
punctate, the punetations having no relation to the extremities of 
the vertical medullary canals 1 . 
The principal forms of tneth of this family were originally referred 
by Agassiz 2 to Psammodus , and placed with this genus in the family 
of Cestraciontidse. Somewhat later, the same author recognized at 
least their generic distinctness, first founding the genera Helodus 
1 R. Owen, Odontography, vol. i. p. 59. 
2 Poiss. Foss. vol. iii. pis. xiv., xv. 
