112 



The shell is half an inch in length, sublriangular, but some- 

 what rounded, slightly compressed, smooth and polished, broad 

 anteriorly, and sloping at the posterior dorsal margin ; the beaks 

 elevated, and the lower margin nearly straight. The animal is 

 everywhere white, nearly transparent. The mantle expands 

 much beyond the margin of the shell, and is open in front, with 

 undulated but unfringed margins. The anterior tentacles are two 

 in number, simple and somewhat longer than the shell. A single 

 ong posterior cirrus arises from the mantle on the dorsal surface, 

 and is kept in continual motion like the anterior ones. The foot 

 is a large, powerful organ, and may be expanded to a length 

 equalling twice that of the shell. The margins of its sole are 

 smooth, and it can be expanded, both horizontally and vertically. 

 Posteriorly, it has a conical process or heel, which bears an 

 opaque byssal gland at its extremity, secreting a glutinous sub- 

 stance, by which this portion of the foot adheres to external 

 objects. There is no true byssus, although this adhesive sub- 

 stance maybe slightly drawn out; but, on the other hand, the 

 pedal process itself may be so extended as to form a mere thread, 

 several times the length of the shell ; and I have often seen the 

 animal, when at rest, suspended in this singular way. 



This species was found at Fort Johnson, in Charleston Harbor, 

 and has since been ascertained to exist on many parts of the coast 

 in that neighborhood. 



Ancistropus sanguineus, Stimpson. 



The animal now to be described is one of the numerous exam- 

 ples of the family Gephyrea of Quatrefages, which occur on our 

 Southern coast. It appears to be by no means an uncommon 

 form, as I have seen examples of the same genus from Florida 

 and the West Indies, and the species called Syrinx papillosus in 

 Forbes's *' British Starfishes " is probably closely allied to it ; 

 but it seems to have as yet received no generic appellation, 

 although its distinctive characters are well-marked. It is allied 

 to Echiurus in its anatomy and in possessing the anterior hooks, 

 but differs from that genus by the absence of posterior seta?, and 

 of the proboscidiform anterior extremity. 



This species inhabits holes in the mud near low water mark, 

 often at the depth of two feet below the surface. Its form when 



