400 Rev. T. R. R. Stebbing on 



is reckoned as 1 + 20 + 2, while in Deiitella it is 1 +.2;+l, and 

 the position of the penes in the former genus is median, in 

 the latter almost median. A key to facilitate the discrimina- 

 tion of the numerous genera is given in three different forms ; 

 but it so happens that in each of these Deiitella and Pseudo- 

 profella are grouped together, instead of being distinguished. 

 As regards the abdomen in the two genera, the illustrations 

 on plate v. seem to show that there is in fact no tenable 

 distinction in this respect between them. It is otherwise with 

 the palp of the mandibles, for its third joint in Deutella is 

 armed with very few setas, while in Pseudoprotella they are 

 numerous. Yet this seems a rather precarious character on 

 which to separate two genera. The species about to be 

 described agrees with Deutella in the simple armature of the 

 mandibular palp, but differs from it and apparently from all 

 other Caprellida? in the shortness of the third joint of the palp, 

 herein making an approach to the genus Farvipalpus, Mayer, 

 in which the third joint is altogether wanting. 



Between I'seudoprotella and Deutella there is one feature of 

 distinction, which Dr. Mayer mentions, though he lays very 

 little stress upon it, but which, in the absence of more striking- 

 differences, acquires some importance. This concerns the 

 relation between the fourth, fifth, and sixth joints of the first 

 gnathopods. In Pseudoprotella the fifth joint or wrist is 

 elongate, so that the fourth joint is kept at a considerable 

 distance from the hand, whereas in Deutella the wrist is so 

 short that the fourth joint almost touches the base of the hand. 



Deutella Mayeri, sp. n. (PL XV. A.) 



The head is rounded and smooth, with the skull-like 

 appearance familiar in Caprella acanthifera. The peraeon is 

 smooth, its third and fourth segments being the longest and 

 equal to one another in length ; the second segment deep in 

 the front pait, at which in both sexes the gnathopods are 

 attached. 



The eyes are round and black in the specimens preserved in 

 spirit. 



Upper Antenna'. — The second joint much longer than either 

 the first or third, the first stouter but very little longer than 

 the third ; the fiagellum having in the male six joints, of 

 which the first is n)uch the longest and carries four hyaline 

 filaments, eacli of the others having but one. In the female 

 the flagellum has five joints. 



Lower Antennce. — Much more slender than the upper, the 

 peduncles of which they do not quite equal in length. The 



