212 CRUSTACEA MALACOSTRACA. III. 



I have little to add to the excellent figures and description of Sars. The largest female measures 

 3-4 mm. in the median line. On a small female attached to the dorsal surface of the carapace of Ery- 

 throps serrata G. O. S. I found a larva in second stage. Sars has figured both the larva and its head 

 from below, but as the last-named figure is too small and indistinct I have drawn the head from 

 below (fig. i6a). It is seen that the antennulse differ much from those in Dajus mysidis. First joint 

 has in my specimen a part overlapped by the sucking-disk; its outer margin is somewhat sinuate 

 and on the anterior half with three low protuberances, each bearing a seta; second joint is very broad 

 but much shorter than in Dajus, with the posterior angle produced into a small, oblong, acute tooth, 

 and the outer margin most peculiarly armed somewhat before the middle -- but perhaps this arma- 

 ture belongs to a third joint otherwise not visible; the rami in the main as in Dajus. The sucking- 

 disk much smaller than in Dajus; it has a moderately narrow rim of pellucid membrane around its 

 whole margin, while an area inside this margin is, as in Dajus, finely sculptured. Hand of seventh 

 pair of thoracic legs (fig. 16 b) much narrower than in Dajus mysidis, not quite three times as long as 

 broad; the distal lappet is very short with five long and fine branches; the proximal lappet not visible, 

 but its three branches are well developed. Length of the larva 0-57 mm. 



Occurrence. The material has been gathered by the "Thor" at a single station. 

 South-West of Iceland: Lat. 6346' N., Long. 2256' W., 80 fath.; 12 females, most of them with 



males. Of the females 2 are attached to the back of the carapace of 

 Erythrops serrata G. O. S.; a third, large female to the upper side of 

 first peduncular joint of Mysidopsis didelphys Norm.; the other females 

 without their hosts. 



Distribution. Taken on a specimen of Erythrops sp. at Kristineberg, Bohuslan (Stephensen). 

 Not infrequent at the south and west coasts of Norway, northwards at least to Lofoten, on Erythrops 

 serrata G. O. S., R erythrophthalma Goes, E. elegans G. O. S., . microphthalma G. O. S., Parerythrops 

 obcsa G. O. S., and Mysidopsis didelphys Norm. Furthermore taken at Scotland in the Firth of Clyde 

 and the Upper Loch Fyne, on Erythrops serrata and E. elegans (T. Scott), and off the west coast of 

 Ireland on Mysidopsis didelphys, 112 and 199 fath. (Tattersall). 



Family Cryptoniscidae. 



This family comprises the forms on which Giard & Bonnier and later Bonnier established seven 

 families in all: Hemioniscidse, Cyproniscidae, Liriopsidse, Asconiscidse, Crioniscidae, Podasconidae and 

 Cabiropsidse. It is well known that the male and the second larval stage are completely identical in 

 all external features; excellent characters for genera and species are found above all in the presence 

 or absence of eyes, and in the first joint of the antennulae and the three posterior pairs of thoracic 

 legs; a somewhat detailed investigation of characters in six forms of larvae is found in my above-named 

 paper dealing with Isopoda, etc., from the German Plankton-Expedition. The females are always much 

 reduced, but yet in very different degree, and while the majority are free in the marsupia of their 



