NATURAL SCIENCES OP PHILADELPHIA. 477 



lated or jagged at its edge near its termination. Both the posterior and ante- 

 rior edges of the valves, which are inclined to solidity, are rectilinear, the 

 front being nearly perpendicular, the hinder much more oblique ; but in the 

 young these sides are rather more parallel, and the central, or linguiform por- 

 tion of the shell, much more narrow. The ventral apex is narrow, but not 

 acute, and its internal tubercle rather broad and compressed. The pallets are 

 very curious, and of a sponge-like look and color. They are remarkably large, 

 in some measure resemble a quill in shape, are usually more or less curved, 

 and have their stalk or unbarbed portion most minutely tuberculated. The 

 upper portion, which is usually about one-half of the entire length, and even 

 at its broadest part scarcely wider than the stalk, is closely articulated ; the 

 upper and concave edge of each joint terminating at either extremity in an 

 ascending filament, is adorned on one side with a very fine fringe of similar 

 but more minute filaments. The joints towards the extremity appear in the 

 few specimens we have seen to lose their lateral filament, and the concavity 

 of the upper edges so increases as to form a decided angle near their middle. 



The tube, which we have not seen ourselves, is declared by Dr. Turton to 

 be thicker and stronger than that of Norvagica, and simple in its outer 

 orifice ; and by Mr. Gray (1827) to be not concamerated. The diameter of the 

 valves, from which our description was drawn up, is about four-sevenths of an 

 inch, whilst the pallets are actually three inches in length, and about two 

 inches broad at the widest part. 



These dimensions, however, especially that of the pallet, are greatly ex- 

 ceeded in the Sumatran examples, from whence we may reasonably conclude 

 that that country is in all possibility its native habitat. Specimens are ex- 

 tremely rare." Forbes 8p Hartley. 



Mr. Jeffreys remarks that "this species requires further investigation, be- 

 cause of the similarity of its valves to those of T. malleolus, and of its 

 pallets to those of T. pennatifera. The former, however, appear to pre- 

 sent a difference in being more arched and solid than in T. malleolus, with 

 the anterior auricle larger and having more striae, as well as in the posterior 

 auricle being usually smaller ; and the latter in having a shorter and much 

 thicker stalk than in T. pennatifera, which is not annular or tracheiform as 

 in that species, as well as in the lateral filaments being shorter and less 

 slender/' 



X. cucullata, Norman. 



X. cucullata, Norman, MSS. Jeffreys, Ann. and Mag. Nat. Hist. 3d 

 ser. vi. p. 125. 



Hah. In drift fir wood at Guernsey : in teak, with T. fimbriataat Belfast. 



Description. " Tube long, thick, not easily detached from the wood, inter- 

 nally wrinkled near the opening. Valves roundish-oval, rather convex ; 

 body marked transversely, but regularly, with a few striaj or impressed lines : 

 anterior auricle small, angle obtuse, stria? numerous ; posterior auricle dila- 

 ted and appressed, having its apex nearly on a level with the crown or umbo 

 of the valve, inner edge free and overlapping the body ; fang broad ; tubercle 

 small ; apophysis sickle-shaped. Pallets composed of 20-30 calciform points 

 or cuculli, which are broad on the outer surface, and slightly overlap one 

 another in succession, lateral edges setaceous, with short filaments ; stalks 

 cylindrical, of same length as pallet. Dimensions: length (of valves) 8-20"; 

 breadth 6-20". 



"The pallets resemble those of T. minima, Blainville (T. palmulata, 

 Philippi) in having the front margin quite plain ; but they differ in the joints 

 being of nearly equal breadth, and (especially in the earlier stage of growth) 

 being much more numerous and compact. 



" The pallets of T. cucullata are also three or four times as long as those 

 of T. minima. The tube and valves of each species are easily distinguish- 

 able. ' ' Jeffreys. 



1862.] 33 



