108 



preceding segment. Caudal rami short, quadrangular in form, being scarcely 

 longer than they are broad, and transversely truncated at the end; apical setse 

 of moderate length, the outer mediate one remarkably thickened in its middle 

 part. Anterior antennae not nearly attaining the length of the cephalic segment 

 and rather narrow, being composed of 17 joints sparingly clothed with com- 

 paratively small setse, proximal division well marked off from the distal one, 

 terminal part uniarticulate. Posterior antennae with the 2nd (basal) joint 

 rather slender, rudimentary outer rarnus attached near the end of this joint; 

 terminal joint very small, but with the apical spine rather strong. Siphon 

 extending about to the end of the anterior division of the body, being, 

 as a rule, conspicuously curved, and in preserved specimens often split up into 

 its two components, the anterior and posterior lips. 1st pair of natatory legs 

 with the spine, issuing from the 2nd basal joint inside, lanceolate in form; terminal 

 joint of outer ramus with only 2 seise, inside, distal spine of outer edge well 

 developed, the other 2 very small. Same joint in 2nd and 3rd pairs with 4. in 

 4th pair with 3 setae inside. Terminal joint of inner ramus in 1st pair with a 

 conspicuous dentiform projection inside the tip; same joint in 4th pair with only 

 a single apical spine. Last pair of legs with the inner expansion of proximal 

 joint broadly rounded, unarmed; distal joint oval in form, with the edges 

 minutely ciliated and the tip provided with 3 comparatively short seta3, the middle 

 one spiniform. 



Male resembling the female in the general shape of the body, but of 

 smaller size, and having the tail composed of 4 well defined segments, the 1st 

 of which is considerably swollen, to receive the comparatively large globular 

 spermatophores- Anterior antennae much more powerfully developed than in 

 female, though composed of a smaller number of joints, viz., 15, the last 2 of 

 which form together a movable terminal section, which admits of being bent 

 upon the somewhat thickened adjoining part of the antenna. 



Body (in female) rather pellucid, with a faint orange tinge, and with 

 the translucent ovarial tubes of a somewhat darker hue. 



Length of adult female about 1 mm., of male 0.7<> mm. 



Remarks. This form, as mentioned above, was at first described by Scott 

 as a species of the genus Acontioplwrus. apparently on account of the somewhat 

 similar structure of the siphon. Its generic difference has however subsequently 

 been admitted by that author, and it was redescribed under the above name in 

 the sixteenth Annual Eeport of the Fishery Board for Scotland. From the 

 nearly-allied Neapolitan species, S. longifurca Giesbr., it is easily distinguished 

 by the very short caudal rami. 



