86 CRUSTACEA MALACOSTRACA. III. 



Nannoniscoides 



n. g;en. 



Description (based on a mutilated male). Body considerably depressed. Head peculiarly 

 shaped; the front area is limited by a pair of exceedingly high and thick keels, and at each side the 

 head is produced into a very large, thick, oblong, subtriangular process directed somewhat outwards 

 and then curved forwards, so that the proximal parts of the antenuulse and antenna; are situated in 

 a hollowing between the process and the keel. — Antennulae inserted considerably from the lateral 

 margins, short; first joint thick and somewhat short; second joint slender and rather short; flagellum 

 with few joints. Antenine lost, excepting the four proximal joints; squama very short. — Mouth-parts 

 nearly as in Nannoniscus ; right mandible (fig. 2 c) has the incisive part somewhat long, several setae, 

 and the molar process moderately short, tapering to the moderately narrow, setiferous end, and directed 

 considerably backwards; maxillipeds (fig. 2 e) long, second joint a little more than twice as long as 

 broad, and its long lobe twice as long as broad; third and fourth joints very broad, and the fourth 

 about as broad as long; fifth joint considerably narrower than the fourth; sixth joint short and some- 

 what broad, without any real lobe; seventh joint small; epipod triangular, long, acute, slightly more 

 than three times as long as broad. 



First thoracic segment considerably narrower than the head, with the sides rounded and no 

 epimeral processes; second segment much broader than the first, at each side produced forwards into 

 a large, triangular process directed forwards and a little outwards, while the other segments have no 

 processes. Third segment is narrower than the second and broader than the fourth, and from the 

 fourth the segments increase in breadth to abdomen. Seventh segment is short, and the median part 

 of its dorsal surface so completely fused with sixth segment that no limit is seen. — (Legs mutilated). 



Abdomen broad, much broader than long. Male operculum somewhat large (fig. 2 d), with 

 the median lamella very broad and near the end produced much outwards. — Uropods ventral, very 

 small, biramous. 



Remarks. This genus is easily separated by the shape of the head and the anterior thoracic 

 segments from all other forms. It is intermediate between Nannoniscclla and Nannoniscus. agreeing 

 with the former and differing from the latter of these genera in having the antennulae normal, while 

 it agrees with the latter and differs from the former in having the median dorsal part of sixth and 

 seventh thoracic segments completely fused. 



Only a single species is known. 



53. Nannoniscoides angulatus n. sp. 

 (PI. VIII, figs. 2 a— 2 e.) 



Male (mutilated). Body not fully three times as long as broad, with the lateral parts some- 

 what expanded. — Head (fig. 2 b) almost twice as broad as long; the thick and high upper keels con- 

 verge somewhat forwards and protrude considerably beyond the anterior transverse and straight mar- 

 gin of the front area. The lateral processes are deep, being triangularly keeled above, considerably 

 longer than broad, with the end obtuse. - Antennulae somewhat shorter than the head; flagellum 



