76 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.53. 



Remarks. — This genus was founded upon a single specimen, which 

 could be examined only superficially for its external charncters. The 

 new material here presented has slightly modified some of the char- 

 acters and has added many new ones. Especial attention is called to 

 the asymmetry of the body, which is comparatively slight in this 

 genus, but which forms an initial step leading up to the complete 

 distortion exhibited in the new genus GolUpravus (p. 78). The ele- 

 vation of the vulvae toward the dorsal surface is also worthy of 

 note; in the new species, diversus, they are practically on a level 

 with the dorsal surface. 



The discovery of the two pairs of antennae and the two additional 

 pairs of legs is particularly gratifying, since it makes this genus 

 completely analogous with the others in the family. It is also very 

 pleasing to find that the internal anatomy fully corroborates the 

 asymmetry of the exterior. 



PHRIXOCEPHALUS TRIANGULUS, new species. 



Plate 9. figs. 80-84 ; plate 10, fig. 85. 



Host and record of specimens. — Three females with egg strings 

 were obtained from the eyes of Neopercis midtifasciata at Owari Bay, 

 Japan, by the Bureau of Fisheries steamer Albatross in 1906. One of 

 these was a perfect specimen and is made the type of the new species, 

 with Cat. No. 47799, U.S.N.M. The others become paratypes, with 

 Cat. No. 47808, U.S.N.M. 



Specific characters of female. — Cephalothorax barrel-shaped, a 

 little longer than wide, made up of the head and first two thorax seg- 

 ments fused, and separated from the third thorax segment by a dis- 

 tinct groove. Anterior end squarely truncated and giving off three 

 frontal processes in the form of short, lobed, chitin horns; a pair of 

 large lateral horns curve over dorsally and send off rows of long 

 posterior branches, more or less anastomosed. Third segment sepa- 

 rated from the fourth by a groove; fourth segment somev/hnt 

 enlarged, especially on the ventral surface, and armed with two 

 lateral and a ventral horn in the form of large chitin spines. Neck 

 behind the fourth segment considerably narrowed, chitinized, and 

 joined to the anterior end of the trunk at a right angle; in the two 

 larger specimens it is at the extreme right anterior corner, in the 

 smallest specimen, about half the size of the other two but with egg 

 strings, the neck is on the midline of the dorsal surface, but a short 

 distance behind the anterior end. The head and neck are also twisted 

 through an arc of 90°, so that the ventral surface of the neck faces 

 inward toward the midline of the trunk. The latter is triangular in 

 side view, considerably flattened laterally, and thickest at the poste- 

 rior end; dorsal surface flat and nearly straight, ventral surface 

 strongly convex; abdomen a small hemisphere at the posterior end 



