NATURAL SCIENCES OP PHILADELPHIA. 157 



pressed, with a sharp arcuated anterior margin. Caudal stylets all with 

 equal rami ; last pair with the rami very short and flattened, the outer one 

 armed with small hooks at its extremity. Telson small, obtuse-triangular. 



Length of the body in a female, 1-2 ; height at the fifth thoracic segment, 

 epimera included, 0-25 inch. 



Found about low-water mark. 



Ahonyx filiger. 



Head with a strong triangular process on each side beneath the base of the 

 superior antennae ; extremity of this process not acute. Superior antennae 

 very short, about as long as the head, with a long, thick pencil of hair on the 

 inner side of each ; basal joint large, with a strong protuberance above, 

 forming a prominent angle at its anterior extremity ; flagellum seven-jointed, 

 the first joint constituting one-third of its length ; accessary flagellum tri- 

 articulate. Inferior antennae longer than the body; the peduncle, however, 

 constitutes but a small part of their length, being but little larger than the 

 superior antennas ; the very slender filiform flagellum appears as if serrated 

 above, but is not provided with calceolae. The first pair of feet in our sin- 

 gle specimen appear to be pointed and simple, the dactylus not being re- 

 tracted against the manus, which has no palm ; second pair with a minute 

 truncate hand, supporting a small tuft of hair at the base of the dactylus. 



The dorsum in this species is sharp, or carinated, but not dentated, being 

 entire and smooth in outline for the greater part of its length, and similar in 

 the thoracic and first three abdominal segments. There is, however, a deep, 

 triangular sinus between the third and fourth abdominal segments, the latter 

 being strongly protuberant, projecting over the very small fifth segment. The 

 second abdominal segment is subtruncate below, and has a deep semicircular 

 siDus on the anterior lateral margin, near its lower extremity. Rami of the 

 last pair of caudal stylets shorter than those of the second pair, and telson 

 rather elongated and slit in two down the middle. 



Length about one-third of an inch. 



It resembles an English species of which a figure has been privately circu- 

 lated by C. Spence Bate, Esq., under the name of " Lysianassa chausica M. 

 Edw." 



Dredged in deep water, by Lieut. White. 



Gammarus subteker. 



A small, compressed species of rather soft and delicate structure. Dorsum 

 rounded. Epimera moderately large. Eye broad-oval, nearly round. An- 

 tennae of both pairs very slender ; superior ones as long as the body. Basal 

 joint more than twice as thick as the next, but shorter ; third joint less than 

 half as long as the second ; flagellum with about thirty articulations ; acces- 

 sory flagellum nearly twice as long as the last joint of the peduncle. 



Inferior antennae nearly three-fourfhs as long as the superior ones ; first 

 joint of the peduncle armed beneath with a sharp process, which nearly 

 reaches the end of the second ; third joint more than twice as long as the 

 first ; fourth shorter than third ; flagellum two-thirds as long as the pe- 

 duncle. 



Second gnathopod with merus and carpus acute below ; haud subovate, 

 twice as long as broad ; palm oblique, with a small, sharp tooth at its pos- 

 terior extremity, reached by the tip of the finger when closed. First, second 

 and third joints of the abdomen armed above with a sharp central spine on 

 the posterior margin, and with four or five minute spines, or sharp comb-like 

 teeth on each side of the middle spine, the margin bearing these latter spines 

 being a little concave. At the corresponding part of the fourth and fifth ab- 

 dominal segments, there are also two or three spines similar to the central 



1864.] 



