MUSEUM OF COMPARATIVE ZOOLOGY. 127 



Description of Sjjecies. 



Waldheirnia floridana Pourt. 



Shell ventricose, triangular, smooth, wider than long, the widest part 

 being across the front; horn-color. Both valves very convex, the larger one 

 with a shallow longitudinal sinus near the front. Lateral margin of 1 irger 

 valve convex, frontal margin angularly sinuous, and deeply indenting the 

 smaller valve in the middle. Front straight and flattened. Beak prom- 

 inent and compressed laterally, with a round and rather largo for 

 Deltidium small, in two pieces. Loop very long, reaching nearly to the 

 frontal margin of the shell, formed of very thin crura, and a very broad 

 ribbon-shaped reflexed portion. Septum well developed. Lines of growth 

 distinct. Length of shell | of an inch, breadth 1 inch. 



V. rv young specimens are flatter, rounder, and have a straight margin ; 

 they could scarcely be distinguished from the young of Terebratula cubensis, 

 if it was not for the loop and septum seen by transparency. There is also 

 some variety of form in the old; in some specimens the length is greater 

 than the breadth, and there is considerable diversity in the sinuosity of the 

 frontal margin. 



This species is quite common off the Florida reef, between 110 and 200 

 fathoms, on rocky bottom : it is always associated with Terebratula cubensis, 

 the latter being still more common (in the proportion of about three to 

 one), and making its first appearance in 100 fathoms. 



Cuvieria operculata Pourt. 



Body oval, flattened, covered with finely and sparsely granulated scales, 

 very compactly imbricated, but overlapping very little except near the 

 mouth and anus. A double row of suckers surrounds the soil abdominal 

 disc, those of the outer row perforating the marginal plates; sometimes 

 two or three' suckers indicate a tendency towards a median row near the 

 anterior end. Ten tentacles, of winch two are much smaller than the rest. 

 (Esophagial ring often pieces shaped like the letter T. The aperture 

 through which the head and tentacles are retracted is closed by five large 

 triangular plates-, alternating with and covering live narrow, tooth-shaped 

 ones. In the young the five plates form a very regular pentagonal shield. 

 In the old they close less accurately, and their outside edges are covered by 

 some overlapping body plates. The anus is closed in the same way, but 

 the plates are much less regular or const int. 



Length 1* inches; breadth jj of an inch. Color light gray. 



Not uncommon; in 120 to 150 fathoms off Sund Key. 



