NATURAL SCIENCES OF PHILADELPHIA. 105 



Habitat. Common species of the Southern Atlantic coast. Very common 

 in the Delaware Bay. In the Academy's collection are four specimens from 

 the coast of Long Island ; and one from West Africa, by Duchaillu. 



Libinia canaliculata, Say. Jour. Acad. Nat. Sc. vol. 1, p. 77, pi. 4, fig. i, 



L. emarginata, Leach. 



In the median line of the body, counting backward from the depression sep- 

 arating the stomach from the genital region, there is a row of five spines ; one 

 in the genital region, two in the cardiac and two in the intestinal. On the 

 gastric region there is a longitudinal row of four spines. The second one 

 counting from behind forward is generally double. The anterior one is situ- 

 ated in front of the transverse row, which contains four spines or tubercles 

 two on each side. The hepatic region always presents more than one spinej 

 usually three, sometimes more ; sometimes three on one side and two on the 

 other. One large spine situated on the posterior part of the branchial region 

 on a line with the lower spine on the intestinal region, another smaller" one 

 intervening between. The whole surface of the carapax studded over with 

 numerous spines and tubercles arranged more or less regularly. The spiues 

 on the lateral margin not as prominent as in L. dubia, but of the same num- 

 ber. 



The cleft of the bifurcated extremity of the rostrum is very shallow. The 

 teeth of the rostrum not on the same plane as in L. dubia, they present a di- 

 rection downward. In the largest specimens the anterior extremity is consid- 

 erably hooked. 



The characters here enumerated as distinguishing L. canaliculata will be 

 found to hold good through all variations of size in those that are no more 

 than an inch in length, as well as in those that are from four to five inches 

 long, the latter being the largest of the kind that I have ever seen. 



Habitat. Common to the North Atlantic coast, but extends down to the West 

 Indies. 



Libinia affinis, Randell. Jour. Acad. Nat. Sc. vol. VIII, p. 107. 



Gibbes says of this species that it "so closely resembles L. dubia, that if 

 from the Atlantic coast, I should not regard it as different, but as it comes 

 from Upper California I cannot venture to pronounce it the same." 



The author here quoted undoubtedly made a mistake when he said that L.ajfinis 

 closely resembles L. dubia. Stimpson approached the truth more nearly when 

 he stated that "it is very closely allied to L. canaliculata." It is undoubtedly 

 nothing more than the young of canaliculata. That it is so will be evident to 

 any one who will take ihe trouble to compare them closely. It agrees with 

 L. canaliculata in every respect excepting size. 



Libinia subspinosa, Streets, n. s. 



Carapax pyriform. Regions distinct. Spines and tubercles few. Three 

 small tubercles arranged transversely on the anterior portion of the gastric 

 region, one on the median line and one on each side. On the posterior part 

 of the stomach, in the usual situation of a spine or tubercle, there is a slight 

 elevation. Genital region compressed from before backward. Two spines on 

 the cardiac region, and one, rather large, on the intestinal region. Five 

 spines on the lateral margin of the branchial region ; the posterior one large. 

 On the upper portion of the same region, near the superior border, are two 

 more, arranged in a line from before backward. Hepatic region devoid of 

 spines, smooth. Just beneath this region, on the antero-lateral border, are 

 two spines, the anterior one large. 



Rostrum prominent; teeth short and their apices directed forward and 

 toward each other. A short obtuse spine projecting over the inner canthus 

 of the eye. On the inferior border of the orbit are two small tubercles. Ex- 

 ternal antennae cylindrical. 



Anterior pair of feet shorter than the second. The fingers come in contact 



1870.] 



