Tertian,.-] PALEONTOLOGY OF VICTORIA. IMoUusca. 



Plate XXXVIII., Figs. l-ld. 

 SPONDYLUS GADEROPOIDES (McCoy). 



[Genus SPONDYLUS (Lin.). (Sub-kingd. MoUusca. Class LamelUbranchiata. Order 

 Pleuroconcha. Fam. Spondylidas.) 



Gen. Char. — Shell irregular, inequivalve, inequilateral ; hinge-line short, straight, forming 

 quadrate ears on each side of the beaks ; a flat triangular cardinal area divided longitudinally 

 by a median cartilage groove which separates the beak of the large attached valve from the 

 hinge-line ; 2 large cardinal teeth in each valve with pits for opposite teeth, and a triangular 

 central cartilage pit connected with groove of cardinal area ; ligament simple, external ; adductor 

 impressions large, rounded a little on the posterior side of middle ; pallial scar, strong, entire ; 

 surface rough spiny. 



Mesozoic to recent warm seas In deep water attached to corals or rocks.] 



Description. — Obliquely ovato-trigonal, gibbous, surface radiated with very- 

 irregular close small ridges of very unequal siees, 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 striae, from ^ to 1 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 



{>rominent concentric scale-like laminae near the beak and on the sides ; average 

 ength of large valve from beak to front margin, 5 inches ; proportional length 

 from hinge-line (and length of smaller valve), ^y^ ; greatest width, ^'^jy ; depth 

 of larger valve, ^y^ ; depth of small valve very variable. 



This fine species of Spondylus varies greatly in the convexity of 

 the upper valve, and in the number of the thick spinose ridges on 

 each valve ; these are from 1 to 3 lines in width, and set with 

 large depressed spines more closely placed towards the margin. It 

 is quite unlike any shell living in the Victorian waters, and differs 

 from the recent and Tertiary S. gaderopus in the much fewer, 

 thicker, and stronger spinose ridges, and the much more numerous 

 unequal and more closely spinulose intervening striae. At first 

 glance it approaches more nearly to the living Spoiidylus Sinensis 

 and S. imperialism but difiers in its much more numerous inter- 

 mediate striae, and their much more numerous regular close smaller 

 spinulose scales. It approaches slightly nearer to the radiation of 

 the recent S. Ducalis, from which it differs in all other respects. 



The S. bifrons of Munster from the Osnabriick beds is the 

 nearest analogue amongst fossil species, but ours is much larger, 



[2?] 



