402 DR. GWYN JEFFREYS ON MOLLUSCA OF THE [Apr. 16, 



triangular : skeleton or apophysary process in lower valve consisting 

 of a simple loop, which is attached to the hinge by short and stout 

 crura, ending in proportionally large triangular upright points or 

 spurs, from which proceeds the obtusely angular or nearly semicir- 

 cular portion of the loop at the base ; the outer surface of the crura 

 is minutely and closely ridged across : inside furnished with about 

 10 ribs, but not with any intermediate striae ; edge notched to corre- 

 spond with the furrows. L. 0*1, B. - 085. 



'Porcupine ' Exp., 1870 : St. 17a, 795 f. A single (upper) valve 

 only. 



I have also, through the kindness of Professor Loven, a perfect 

 specimen from the Josephine Bank off the Strait of Gibraltar, which 

 was dredged in 340-430 fathoms. 



The peculiar shape and sculpture serve to distinguish this tiny 

 species from the young of T. caput-serpentis, and from the next 

 species T. trigona. 



3. Terebratula trigona 1 , Jeffreys. (Plate XXII. fig 3.) 

 Shell triangular, much compressed, solid for its size, semi- 

 transparent between the ribs, and glossy : sculpture, 8 rounded 

 longitudinal ribs, which radiate from the beak, and become gradually 

 broader towards the front ; those in the middle of each valve are the 

 largest ; the ribs are strongly wrinkled across by the lines of growth ; 

 the interstices or furrows are narrow : ccecal tubuli numerous and 

 close-set : colour clear white : margins gently curved and scalloped 

 in front, abruptly sloping at the sides, broad or having somewhat 

 ear-like expansions behind : beak short : foramen oval and propor- 

 tionally large, incomplete : deltidium small : hinge-plate thick : 

 teeth in the upper valve short and strong : skeleton in the lower 

 valve consisting of a semicircular loop, which is attached on each 

 side by short and strong crura, and terminate in small pointed spurs : 

 inside of both valves smooth and polished, exhibiting through the 

 shell the thick outside ribs. L= 0*1, B. 0*1. 



A single living specimen was dredged by Mr. Kent, in Mr. Mar- 

 shall Hall's yacht the • Noma,' off the coast of Portugal, in about 

 500 fathoms. He very obligingly gave it to me with a specimen of 

 the following species. It may perhaps be immature ; but I cannot 

 identify it with the young of any other species. 



This pretty little shell differs from the young of T. caput-serpen- 

 tis in shape, colour, having fewer ribs and a smooth interior, and in 

 the loop being rounded instead of incurved at the base. In T. 

 caput-serpentis of the same size as this (PI. XXII. fig. 1) the inside, 

 especially in front, has strong and conspicuous ridges, which become 

 notches in the full-grown shell. 



Typical. Loop short, semianuular. 



4. Terebratula subquadrata 2 , Jeffreys. (Plate XXII. fig. 4.) 

 Shell broadly triangular or oval, with a squarish outline ; upper 



1 Triangular. 2 Somewhat square. 



