286 RATHBUN 



is thin and cut in small shallow teeth, of which there are about 

 seven in front of the notch and fourteen behind it. The orbits are 

 situated about half way between the middle and the lateral angles ; the 

 inner margin of the orbit is erect. The margin of the front is nearly 

 straight except outwardly where it is concave, curving forward to form 

 a strong antero-lateral tooth with a spiniform tip pointing forward. 

 The rostral lobe is divided half way to its base forming two narrow 

 ascending horns separated by a closed fissure. The peduncle of the 

 antennules reaches a little beyond the end of the penult segment of the 

 antennae ; the inner flagellum is much thinner and a little longer than 

 the outer. The leaf-like expansion of the antepenultimate segment of 

 the antenna terminates in a sharp spine; its outer margin has two 

 teeth, its anterior margin one tooth ; the inner margin of this segment 

 as well as of the succeeding segment is erect and bidentate ; the termi- 

 nal segment is sharp-pointed in front ; the margins of the antennae are 

 finely denticulate or crenulate. 



The second to fifth abdominal segments have a convex tubercu- 

 lated median carina ; that on the fourth segment has posteriorly 

 a curved backward-pointing spine ; a similar but smaller spine is on 

 the fifth segment ; the sixth segment has a tubercle either side of the 

 median line and a small posterior median spine ; the seventh segment 

 has a median tubercle on its anterior portion. The lateral margins of 

 the second to seventh segments are divided into several triangulate 

 lobes or teeth ; on the second to sixth segments there is a large com- 

 pound tubercle at the junction of the dorsal surface with the pleura. 

 The meral and carpal joints of the legs have each a superior distal 

 spine. 



Dimensions. — Length of body from the tip of the antennae 39 mm., 

 length of carapace 13.2, width of carapace 18, length of antepenult 

 segment of antenna 7, width of same 8. As the specimen has a very 

 thin soft shell the measurements are only approximately accurate. 



Locality. — One specimen was taken from the stomach of a green 

 turtle, 200 miles north of Clipperton Island, December 8. 



This specimen differs from Miers's description of specimens from 

 Mauritius, chiefly in having a wider carapace, and also a wider ante- 

 penultimate antennal segment, this segment being broader than long 

 instead of longer than broad, as in the figure given by Miers ; the 

 segment is also more strongly dentate in our specimen. Considering 

 the state of the type specimens, dried cast shells, and the half digested 

 condition of the West American example it seems best to consider them 

 probably identical. 



