526 BULLETIN" 15 8, UNITED STATES NATIONAL MUSEUM 



maxillae. The single free segment behind the head much longer 

 than in the other two species of the genus. The remaining thoracic 

 segments are completely fused without any indications of segmenta- 

 tion ; at the posterior end is a pair of caudal rami close together on 

 either side of the midline. In front of them on the ventral surface 

 is a pair of short dactylose processes, bluntly rounded at their tips; 

 the abdomen is lacking. 



The first antennae are 3-segmented, with two spines on the end seg- 

 ment and one spine on the penultimate segment. The second anten- 

 nae are broad and flattened, the basal portion 2-segmented, the 

 endopod 1-segmented and bluntly rounded, with a spine on the inner 

 margin near the tip. The exopod is 2-segmented, the end segment 

 with a stout acuminate spine at its inner distal corner, a much 

 smaller spine at the outer corner, and between them two still smaller 

 spines. The first maxillae are tipped with three stout spines, the 

 palp with a single short spine. The second maxillae are long and 

 slender, each tipped with a stout curved claw, whose point shuts 

 into a bipartite process on the end segment forming a chela. The 

 basal segments of the maxillipeds are fused across the midline, the 

 terminal claws are short and strongly curved. Total length, 

 1.6-1.8 mm. 



Metanavj'plius larva. — Two of the adult females carried ripe eggs, 

 which were successfully hatched on being placed in an aquarium. As 

 these are the first embryos to be obtained of any species belonging 

 to the family Sphyriidae, they become of considerable interest. As 

 in the Lernaeopodidae the nauplius and metanauplius stages are 

 passed inside the ^^^^ and the larva escapes from the egg at the 

 close of the metanauplius period ready to molt into the first copepo- 

 did, or free-swimming, stage. 



The body of the metanauplius is stout and ellipsoidal, the head is 

 still fused with the first segment, but the second segment and abdo- 

 men are well defined, and the latter carries a pair of caudal rami. 

 The first antennae are 3-segmented ; the end segment still retains its 

 two apical setae but carries also a well-developed claw inside the 

 skin. The second antennae are biramose, the exopod 5-segmented, 

 each segment armed with a plumose seta, the endopod 1-segmented, 

 retaining the two terminal setae but with a claw inside the skin as 

 in the first pair. The first maxilla is a dactylose process tipped with 

 two setae, removed to the vicinity of the lateral margin. The sec- 

 ond maxillae and maxillipeds are each stout, uniramose, indistinctly 

 3-segmented, the end segment with a slender apical claw. The two 

 pairs of swimming legs are very rudimentary, each leg consisting of 

 a basal segment and two 1-segmented rami armed with long plumose 

 setae; the caudal rami are as large as the leg rami and two of the 

 apical setae on each ramus are enlarged at the base. 



