43 



Rostrum short, elevated, compressed, armed— when armed — dorsally only. 

 Cervical groove very distinct. There is a post-antennal (branchiostegal) spine, 

 and the orbital angle may be acute. No hepatic spine. 



Byestalks depressed and flattened, with a tubercle on their inner face : eyes 

 often a little deficient in pigment. 



The basal joint of the antennular peduncle is hollowed for the eye, and its 

 outer edge is armed with one, or two, spines, but there is no scale on the inner 

 edge. Both the antennular flagella are long, and the upper one, which springs 

 from near the apex of the peduncle, is thickened in its basal part. Antenna! 

 scale very large : antennal flagellum long. 



Mandibular palp foliaceous, reaching to the base of the antennules : the 2nd 

 joint is a good deal narrower and shorter than the 1st. 



Palp of the 1st maxilla? slender, single- jointed. The exopodite of the 2nd 

 maxillipeds is very much longer than the endopodite : the endopodite is pediform, 

 its last 3 joints are flexed on the merus, and the dactylus has some tiny spinules 

 at tip. The exopodite of the external maxillipeds is like that of the 2nd maxilli- 

 peds but shorter: the endopodite is stout and pediform with a short dactylus that 

 has some tiny spinules at tip. 



The first 3 pairs of legs are slender subcylindrical and chelate, the fingers 

 of the chelaa being about as long as the palm. The last 2 pairs are mono- 

 dactylus and still more slender than the others. 



The abdominal appendages are slender, the exopodites being longer than 

 the endopodites, especially in the anterior somites : the first pair of appendages 

 carry only an exopodite, and, in the male, a triangular " petasma " or 

 " andricum : " in the 2nd of pair appendages, in the male, the endopodite has a 

 pair of little scale-like lobes — one behind the other — at its base. At least the 

 first abdominal sternum is vertically produced, or subacute, in the middle line. 



Epipodites are present on the first four, and podobranchiaa on the first 

 three, pairs of legs. Pleurobranchiaa of normal size are present on the last 7 

 thoracic somites. 



The branchial formula is as follows : — 



„ ., , Arthi'obranchire. 



