1879.] THE COREAN AND JAPANESE SEAS. 57 



This species has apparently a very wide geographical range, as 

 there are specimens which do not seem to differ specifically in the 

 British Museum from the Gulf of Suez and Western Australia ; and 

 I am informed in a letter from Mr. J. S. Kingsley, of the Peabody 

 Academy of Science, Massachusetts, that the. Museum of that In- 

 stitution possesses specimens from Hong-Kong, the Sandwich Islands, 

 and Zanzibar. 



CUM ACE A. 



Heterocuma, gen. nov. 



Cephalothorax without a distinct rostrum, and (viewed laterally) 

 nearly straight in its dorsal outline. Five free segments of the body 

 exposed. Postabdomen much longer than the carapace, terminal 

 segment obsolete. Eye large and distinct. Antenuules robust, 5- 

 jointed, without any accessory flagellum, and with the first three 

 joints of the peduncle dilated. Mandibles with the apex strongly 

 dentated, the inner margins armed with 10-12 stiff setae and with 

 a prominent molar tubercle. First maxillae with the slender flagella 

 terminating in two unequal setae. First and second maxillipeds 6- 

 jointed ; third maxiUipeds 6-jointed, the basal joint considerably 

 dilated, and produced at its extero-distal angle, which is subacute, 

 the second joint very short, transverse, the third with its extero-dis- 

 tal angle greatly produced and acuminated, the fourth dilated and 

 truncated at its distal extremity, and the fifth and sixth slender. 

 First three pairs of legs palpigerous in both sexes. The appendages 

 of the sixth postabdominal segment (uropoda) are elongated, the 

 basal portion being about as long as the fifth postabdominal segment, 

 and terminating in two flattened subequal rami, which are two- 

 jointed and about as long as the base. 



In the males there exist well-developed appendages on the ventral 

 surface of the first five postabdominal segments, and the antennae 

 are well developed and have the last joint of the peduncle dilated and 

 terminate in a slender flagellum, which is directed backward and is 

 as long as the animal. 



This genus is apparently nearly allied to Eudorella, Norman {Eu- 

 dora, S. Bate), which it resembles in general form, the obsolescence 

 of the terminal postabdominal segment, the form of the uropoda, 

 &c., but differs in the existence of a well-developed eye, in the 

 structure of the flagellum of the first maxilla, which terminates in 

 two setEe, and particularly in the dilatation of the third and fourth 

 joints of the third pair of maxillipeds. In the males, moreover, the 

 first five postabdominal segments are all furnished with appendages. 



It is also very nearly allied to Leptocuma, Sars, from Rio Plata, a 

 genus recently described and beautifully figured by its distinguished 

 author in Kongl. Vetensk.-Akad. Handl. xi. no. 5, p. 24 ; but in 

 that genus the eye is indistinct, and not furnished with corneae, the 

 first pair of legs more robust, and, moreover, the third maxillipeds 

 (so far as they could be seen without dissection in the unique 

 specimen) are described as "of perfectly normal structure" in 

 Leptocuma, 



