SCI^ENOPHILUS. 63 



ages somewhat as in Caligus, but the second maxilli- 

 peds very large. Sternal fork absent. Thoracic legs 

 nearly as in Caligus. 



1. Scisenophilus tenuis P. J. van Beneden. 

 (Plate XI, figs. 1-6.) 



1852. Scienopliilus tenuis, P. J. van Beneden. (13) p. 464, and plate. 



1861. Scienopliilus tenuis idem. (15) p. 148, fig. 21. 



1896. Scixnopliilus tenuis Bassett-Smith. (6) p. 156. 



1906. Scisenopliilus tenuis Norman & T. Scott. (88) p. 207. 



Female. Carapace small, suborbicular, length and 

 width about equal. Frontal plates distinct, lunulas 

 small. Free thoracic segment small ; genital segment 

 elongated and narrow, but increasing in width gradu- 

 ally though slightly towards the posterior extremity, 

 the greatest width being equal to about one fourth of 

 the length, and the length equal to about three times 

 the length of the carapace, the distal end slightly 

 emarginate and the postero-lateral corners bluntly 

 rounded. Abdomen extremely long and slender, fully 

 twice the length of the genital segment and about as 

 long as, and not much thicker than, the egg-strings. 

 Caudal rami short, and provided with four to six 

 apical setae. 



Antennules small, two- jointed, and similar to those 

 of Cctlif/us ; mouth -appendages also similar. The 

 second maxillipeds stout and elongated, and armed 

 with strong curved terminal claws. The first pair of 

 thoracic legs slender, and bearing at their distal end 

 three strong and curved setiferous spines ; only the 

 second pair of legs distinctly biramose. The fourth 

 pair elongated and uniramose, and consisting each of 

 two tolerably long joints, the terminal one being fur- 

 nished with a few marginal and apical setse. Total 

 length about 14 mm. (fully half an inch). 



We have not seen the male of this species. 



Habitat. Parasitic in the branchial chamber of the 

 maigre, Scidena aquila (or Sci&na iimbra), Plymouth 

 (Bassett-Smith). 



