281 



Fam. 9. Leucothoidae. 



Body slender, with not very deep coxal plates, the 1st of which are 

 well developed. Cephalon comparatively small, and but little produced in 

 front; metasome of normal appearance. Antennae not very elongated, and of 

 similar structure in the 2 sexes, the superior ones without any secondary 

 appendage. Epistome produced in front. Anterior lip lamellar, bilobed; 

 posterior lip well developed, without any inner lobes. Mandibles strong, cut- 

 ting edge coarsely dentated, molar expansion wanting, palp distinct, though 

 not very large. Maxillae of normal appearance. Maxillipeds without any 

 distinct masticatory lobes, palp very large and pediform. Gnathopoda power- 

 fully developed, and rather complex in structure, the anterior ones having 

 the carpus produced so as to form with the propodos a complete chela, the 

 posterior ones subcheliform, and larger than the anterior. Pereiopoda slender, 

 basal joint of the 3 posterior pairs laminarly expanded. Branchial lamellae 

 simple and rather narrow; incubatory lamellae well developed and fringed 

 with slender setae. Last pair of uropoda biramous. Telson entire. 



Remark*. - The family is here taken in a much more restricted sense 

 than it is by Boeck. The latter author comprised in it, besides the genus 

 Lf'iicotho< : , the 3 genera Enxinis, Tritropis and Uf/jrhort/ifi. But, as recently 

 pointed out by the Rev. Mr. Stebbing, these 3 genera are in fact rather 

 different from Leucothoe, and more properly referable to a particular family, 

 Euxiridrr. In his valuable work on the Challenger Amphipoda Mr. Stebbing 

 has referred to the family Leucothoidae, only one genus in addition to the 

 type one, viz, that named by Costa as Seba. In my opinion, however, this 

 genus cannot properly be associated with the genus Leucothoe, differing 

 as it does in many very essential points, thus in the presence of an acces- 

 sory appendage to the superior antennas, and of distinct masticatory lobes to 

 the maxillipeds. Moreover the gnathopoda in this genus, though showing a 

 remote resemblance to those in Leucothoe in that they are cheliform, are in 

 reality constructed upon a totally different type. Therefore, in my opinion, 

 only the genus Leucothoe ought at present to be referred to the family under 

 question. It is placed here next to the Stenothoidae, as it shows, at least 

 as regards the structure of the maxillipeds, some apparent resemblance to 

 this family, though otherwise very different. 



36 Crustacea. 



