13 



shorter than the cephalosome, and rather densely setiferous at the end of the 

 joints, 1st joint about the length of the remaining joints combined, olfactory 

 filaments 5 in number. Inferior antennae but little shorter than the superior, 

 though somewhat narrower. Chelipeds very strong, hand in female oblong oval 

 and exceeding in length the carpus, both fingers provided inside with an obtuse 

 tubercle; that in male considerably larger, with the fingers distinctly forcipate. 

 1st pair of pereiopoda longer than the others, dactylus Inarticulate and subulate 

 in shape ; the succeeding ones with the carpal joint somew r hat expanded and armed 

 with several strong denticles, dactylus in the 3 posterior pairs very strong, 

 hooked and armed inside in their outer part with comb-like denticles. Uropoda 

 about the length of the last 2 segments of metasome combined, 3-articulate and 

 rather densely setiferous, middle joint the longest, terminal joint rather short. 

 Body whitish, variegated on the dorsal surface with a dark brownish pigment form- 

 ing on the cephalosome a close reticulation, on the segments of mesosome, inter- 

 rupted transversal bands. Length of adult female 5 mm., of male somewhat less. 



Remarks. - - This form has been recorded by Kroyer, as early as in 1842, 

 under the above name, whereas Rathke's description of his Crossurus vittatus dates 

 from the succeeding year. According to the rules of priority therefore, the specific 

 name proposed by Kroyer ought to be preferred to that of Rathke. The T. Cavolini 

 of M.-Edw. is very closely allied to the present species, and the only, in any 

 way essential difference I have found in examining a single specimen of that 

 species, is that the uropoda are 4-articulate instead of 3-articulate. 



Occurrence. - - Rathke found this form on oysters at Molde. It has sub- 

 sequently been observed at Christiansund by v. Diiben, and on the south coast 

 by Orsted. My late father found it at Floro and Manger. I have myself ob- 

 served it rather plentifully in a small bay at Korshavn, south of Bergen, where 

 it occurred in quite shallow water among grass. At Haugesund, farther south, 

 I have found it occasionally in weedy pools left by the tide. 



Distribution. -- Oresund (Kroyer). British Isles (Sp. Bate), Atlantic coast 

 of North America (Harger). 



Gen. 2. Heterotanais, a. o. Sars, isso. 



Generic Characters. Body comparatively short and thick, slightly depressed, 

 and exhibiting a rather different appearance in the two sexes. Metasome nor- 

 mally developed, with all 6 segments well defined. Eyes distinct, placed, as in 



