52 



slight swelling of the carapace on each side at the base of the pseudorostral 

 projection. Appendages of the usual structure. Length 11 mm. 



Remarks. I cannot doubt that this is the form originally recorded by 

 Goodsir as Alauna rostrata. There is no other species of Diastylis, which agrees 

 better with the figure and description given by that author, and its occurrence 

 in comparatively shallow water would also seem to point to the identity of these 

 2 forms. The Diastylis Icevis of Norman is unquestionably the same species. By 

 the perfectly smooth carapace, this form is easily distinguished from any of the 

 preceding species, somewhat resembling in this respect the next species, D. tumida 

 Lilljeborg, which, however, is a true deep-water form, and differs, among other 

 things, in the larger size of the carapace, and in the different shape of the telson. 



Occurrence. I have met with this form only in a few places on the south 

 coast of Norway, viz, in the outer part of the Christiania Fjord, at Farsund, and 

 at Egersund. In all 3 places it occurred in only a few fathom's depth, on a 

 sandy bottom covered by a thin layer of mud. 



Distribution. Kattegat (Meinert), Heligoland (Ehrenbaum), British Isles 

 (Goodsir), Stats. 6, 11, 18 of the Porcupine Expedition (Norman). 



6. Diastylis tumida, (Lilljeborg). 



(PI. XL.) 

 Cuma tumida, Lilljeborg, 0fvers. af Vetensk. Akad. Forliandl. 1855, p. 119. 



Specific Characters. Female. Body rather robust, with the anterior di- 

 vision greatly tumefied, and of rounded ovoid form, with the dorsal face boldly 

 arched. Carapace very large and deep, more than twice as long as the exposed 

 part of the trunk, and considerably vaulted in its posterior part; surface perfectly 

 smooth, only clothed with scattered short hairs; pseudorostral projection not much 

 produced, with the tip very slightly upturned: subrostral corners well marked, 

 almost rectangular. Last pedigerous segment with the lateral parts rounded off 

 behind. Tail about the length of the anterior division, segments simple, unarmed. 

 Eye well developed and rather conspicuous, appearing as a distinctly projecting 

 tubercle at the end of the frontal lobe. Superior antennse slender, with the 

 peduncle reaching far beyond the tip of the pseudorostral projection, its 1st 

 joint shorter than the other 2 combined and unarmed. First pair of legs about 

 the length of the carapace, basal joint much shorter than the remaining part of 

 the leg, the last 3 joints of rather unequal length, the penultimate one being 

 much the longest, last joint comparatively short, not even attaining half the 

 length of the penultimate one; 2nd pair with the ischial joint produced below to 



