ON CRUSTACEA BROUGHT BY DR WILLEY FROM THE SOUTH SEAS. 671 



were labelled " Rubiana, New Georgia, from tail of Albicore." The females with egg- 

 strings attached agree with the figures and description given by the authors above- 

 mentioned. The male differs from the female seemingly much more than is the case 

 with Mr Thomson's New Zealand species, and in a manner that will not suit the generic 

 definition drawn up from the female alone. The genital segment is rounded oblong, not 

 produced into lappets, but having lappets attached at its sides. These lappets are not 

 articulated but marked off by a slight constriction and extend along about two-thirds of 

 the abdomen or pleon ; their outer margin is folded under and ends in two spines, the 

 much more convex inner margin ending separately in a single spine. I am inclined to 

 suppose that they correspond not to the lappets in the female, but to the appendages 

 which project laterally from those lappets and which have the inner margin fringed with 

 twelve or more spinules or denticles. The dorsal plates of the fourth segment of the 

 trunk have theii- inner margins more divergent and oblique in the male than in the 

 female. In both sexes the pleon is two-jointed as described by Thomson, not unjoiuted 

 as described and figured by Steenstrup and Liitken. The filiform caudal appendages, 

 which in the female are considerably shorter than the pleon, in the male nearly equal 

 it in length ; at a point between a quarter and a third of their length they become 

 narrower and have a spinule at the outer margin ; at the apex are three unequal 

 spines. 



Length of female, 12 mm.; of egg-strings, 12 mm.; of specimen including egg-strings, 

 22 mm. ; of male, 10 mm. 



The agreement in habitat and general details leaves no doubt that the males 

 and females belong to the same species. A single specimen, like the males in size, 

 but with dorsal plates as in the female, had very short lappets carrying lateral ap- 

 pendages as large as the normal ones in the female but with only two or three 

 denticles as in those of the male. This may be either a monstrosity or a developing 

 female. 



Fam. Dichelestiidae. 



1898. Dichelesthiina, Bassett-Smith, Ann. Nat. Hist., Ser. 7, vol. 2, p. 91. 



1899. Dichelestiidae, Bassett-Smith, Proc. Zool. Soc. London, p. 468. 



1900. Dichelestiidae, T. Scott, 18th Annual Rep. Fishery Scotland, pt. 3, p. 159. 



Mr Bassett-Smith in 1898 quotes from Gerstaecker a synoptic table of sixteen 

 genera in this family, and then modifies the table to include two new genera of his 

 own. In 1899 he withdraws the genus Baculus, MrAzek having shown that Bacidus 

 Lubbock, and Hessella Brady, are only represented by young forms of the Lernaeid 

 Pennella Oken. At the same time he transfers Philichthys Steenstrup, to a new family 

 Philichthyidae. 



Bassettia, n. gen. 



Head globose. Body naiTowed behind the head, with little or no demarcation of 

 the pedigerous segments, the genital segment oblong oval, wider and longer than all 

 the rest of the animal, having closely connected with it a much narrower short terminal 

 segment, carrying two short and narrow appendages, tipped with minute spinules. First 



