470 PROCEEDINGS OF THE NATIONAL MUSEUM vol.88 



The antennule is like that of the adult, but the proximal segment 

 is lacking. Behind the antennule is the antenna composed of two 

 basal segments with a spine on the posterior side of each. It has 

 an unsegmented palp on the second segment and a 3- jointed distal 

 portion ending in long plumose setae. The antennae are joined to 

 a transverse chitinous bar on each side of wliich is a forward process 

 and a backward spine — the postantennal spine of the adult. 



A small sting is located at the base of the proboscis, which is es- 

 sentially the same as that of the adult except that it is very short. 

 The buccal fold is not yet serrated, and there are no labial processes or 

 labial spines. The mandible is pointed, with an acuminate process 

 on the lower margin near the tip, and the mandibular palp is attached 

 by a chitinous framework at the base of the proboscis just behind the 

 antenna. It is unsegmented, almost as long as the antenna, and ends 

 in three long plumose setae. It is supported at the base by a circular 

 framework of chitin, which forms a thickened area with a spine at 

 the point of attachment. This framework serves to support the 

 proboscis by means of the inner longitudinal rod already differen- 

 tiated and an outer longitudinal rod to be differentiated at the next 

 stage. Thus modified parts of the mandible proper form the supports 

 of the proboscis. 



The first maxillae are found on each side of the proboscis. They 

 consist of three segments of which the basal one is bulky. On the 

 tip are two large curved claws, one with three small processes on its 

 anterior margin. 



On the posterior distal corner of the basal segment of the 5-jointed 

 second maxilla is a spine corresponding to the middle of the three 

 spines found on the adult. The distal segment is provided with two 

 curved claws and a papilla on the tip. Two pairs of spines are 

 located near the midline of the body as in the adult — the postmax- 

 illary spines. 



Only the first pair of thoracic appendages is functional ; the others 

 are rudimentary and immobile, each with an unsegmented exopod 

 and endopod. On the first appendage the coxa, basis, exopod, and 

 jointed endopod are complete, but the precoxa is indistinguishable. 



The abdomen is only about one-tenth as long as the body and has 

 spinules along the posterior ventral side and margin. The caudal 

 furcae are comparatively large. Sexes can be distinguished by the 

 presence of rudimentary testes or small round seminal receptacles. 



Second stage. — After three or four days the first molt takes place, 

 and the animal assumes more the shape of the adult. It attains a 

 length of 0.9 to 1 mm. The anterior margin of the carapace is 

 fringed with ciliary processes as far back as the first maxillae. The 



