DM: THE SHETLAND CRUSTACEA, TUNICATA, ETC. 269 



to the penultimate joint of the peduncle, subquadrate ; external margin 

 smooth, terminating in a spine ; apex obliquely truncate, not extending 

 beyond level of the tip of the spine of outer angle ; inner margin and 

 apex with plumose seta3. Mandible palp three -jointed, last two joints 

 long, subequal, last slender, both setose. Flattened scalar basal joint of 

 pereiopods having a naked external margin, terminating in a spine-like 

 point. Last portion of pereiopod multiarticulate ; in last pair articula- 

 tions thirteen in number, each with a spine on both margins, and spine- 

 like setae on inner margin. Marsupial pouch attached to last pereiopods 

 and first pleopods; the latter composed of a long basal joint (closely resem- 

 bling a thigh-bone in form), naked during its length, but having at the 

 base a little lobe, bearing four long plumose setae, and having its 

 expanded apex surrounded with a circlet of similar long setae, within 

 which the two little branches in which the member terminates nestle ; 

 these branches one-jointed, terminated by setae; one branch half the 

 length of the other. The remaining pleopods, in the form of a narrow 

 scale, furnished with plumose setae. Telson cleft at the apex to about 

 one-fifth of its length ; sides furnished with 79 spines of great size, 

 more especially the distal ones, which are equal in length to the cleft; cleft 

 margined with rather long, sharp, slender serrations. Inner laminae sub- 

 equal in length to (spines of) telson, narrow, fringed with long setae, 

 and inner margin also with about ten slender spines ; acoustic organ 

 unusually small. External laminae shorter than inner, rounded on 

 apex ; outer margin having about twelve greatly developed curved spines 

 instead of the usual plumose setae. 



Male. The male, instead of having a separate lobe to superior antennae, 

 as in My sis, has the first joint of external filament expanded in a similar 

 manner to the female, but is more strongly developed. All the pleopods 

 composed of a large basal joint (in the first furnished with large plumose 

 setae, in the others naked) and two branches; first, fourth, and fifth 

 pairs with outer branch half as long again as peduncle, multiarticulate 

 and setose : inner branch short, with widely diverging plumose setae ; 

 second pair with both branches multiarticulate and plumose, the exter- 

 nal branch rather more developed than the inner, the latter with a 

 small lateral lobe at the base ; third pair having outer branch of consi- 

 derable length, consisting of four long, rounded, slender, smooth joints, 

 the last having two minute marginal spines, and terminating in two 

 slender spines ; inner branch shorter than first joint of outer, multiar- 

 ticulate and plumosely setose ; basal joint giving off a small lateral lobe. 

 Length three-quarters of an inch. 



Dredged 5-8 miles east of Balta, in 40-50 fathoms ; also Banff (Mr. 

 Edward), Firth of Clyde (Mr. D. Robertson), and off the mouth of the 

 Tees and Norfolk coast (Mr. G. S. Brady). 



Genus NEMATOPTJS, G. 0. Sars. 



Allied to Mysis. Superior antennae having first joint of peduncle with a 

 setiferous process on the outer margin ; the last joint in male with a hirsute 

 lobed appendage. Pereiopods very long and slender, 8-jointed, nearly fili- 

 form, with very few hairs, terminating in a well-formed nail. No external 

 branchio3. Marsupial pouch as in Mi/sis. Pleopods in female rudimentarv 

 as in Mysis, but in male well developed, two-branched ; branches multiar- 

 ticulate ; the external branch with a setiferous process on its inner margin ; 

 in the first pair the terminal part rudimentary, and without setae. Telson 



