6P0NDTLUS. 307 



Family SPOKDYLID^. 



Genus SPONDYLUS, Linnteus. 



[Syst. Nat. ed. 10, 1758, p. 690.] 



Shell irregular, inequivalve, attached by the right valve, 

 auriculate, ornamented by radiating costae which are typically 

 spinose or scaly ; right valve more convex than the left, cardinal 

 area triangular, having in the centre a longitudinal groove ; left 

 valve smaller than the right, less convex; hinge of each valve 

 consisting of two large teeth, with corresponding pits on the 

 opposing valve ; muscle impression near the centre of each valve ; 

 pallial line entire. 



Type. — Spondylus gaderopus, Linnaeus. 



Spondylus gaederopoides, M'Coy. 



1876. Spondylns gndcropoides, M'Coy, Prod. Pal. Yict. dec. iv. p. 27, 



pi. xxxviii. figs. l-\d. 



1877. Spondylus gecdcropoides, M'Coy, id. dec. v. p. 17, pi. siv. figs. 1-3. 

 1886. Spondylus gmdtropoides, Tate, Trans. Roy. Soc. South Aust. vol. viii 



p. 121. 

 1893. Spondylus gaderopoides, Tate and Dennant, id. vol. xvii. pt. 1, p. 224. 

 1896. Spondylus gcedcropoides, Pritchard, Proc. Eoy. Soc. Vict. vol. viii. n.s. 



p. 128. 



" Obliquely ovato-trigonal, gibbous, surface radiated with very 

 irregular, close, small ridges of very unequal sizes, often in groups 

 of five, with middle one largest, occasionally alternate, roughened, 

 with close, spinose, transverse scales, usually one to five very small 

 between each pair of larger stria?, from one half to one line in width ; 

 from 4 to 10 thick ridges set with moderately close, variable, long, 

 arched spines, depressed near base, often compressed beyond, 

 generally fewer on the upper than on the lower valve, but 

 sometimes the lower valve with no spinose ridges in the middle 

 portion, but two or three on each side ; the large valve often with 

 prominent concentric, scale-like laminae near the beak and on the 

 sides ; average length of large valve from beak to front margin, 

 5 inches ; proportional length from hinge-line (and length of 



