CRUSTACEA MALACOSTRACA. II. 



anomalus G. O. S. and of species of Leptochelia. — Adult males of some few other species have been 

 described by Moore, Stebbing, etc. 



A study of Sars' descriptions and figures of adult males as compared with the corresponding 

 females is interesting. In Tanais Cavolinii M.-Edw. [T. tomentosus Kr., G. O. S.) female and male seem 

 to differ only by the chelae, which in the male are very broad, strongly forcipate and without tubercles 

 on the fingers, while in the female they are rather slender, scarcely forcipate and with two tubercles 

 on the fixed finger. The males of all other above-mentioned forms differ much more from their 

 females. In Ilctcrotanais Ocrstedii Kr. the male has the cephalothorax produced in a very long and 

 thin "neck", the antennulae and the antennae are longer and thinner than in the female, the antennulae 

 five-jointed in the male, three-jointed in the female, and the chelipeds are quite anomalously shaped 

 in the male, normal in the female. The males known belonging to Paratanais, Typhlotanais, Lepto- 

 gnathia and Cryptocopc differ from their females in many particulars: the antennae are six-jointed when 

 three-jointed in the female, seven-jointed when four-jointed in the female, and have besides in all 

 genera tufts of sensory hairs on three of the joints; the thoracic segments are conspicuously shorter 

 in proportion to carapace and abdomen than in the females; the chelipeds or at least the chelae differ 

 somewhat or considerably in shape and equipment from those of the females: the thoracic legs are 

 somewhat or considerably longer and more slender, the abdomen is larger, its pleopods longer with 

 longer setae and the uropods at least a little longer than in the females; finally in Paratanais the 

 eyes of the males are much larger than in the females. The males of Leptochelia differ from their 

 females especially in having much larger eyes, the chelipeds elongate with the chelae very differently 

 shaped and the antennulae divided into a good number of joints. (It has been stated that in the 

 males the mouth-parts are generally more or less reduced, but the majority of the males described 

 have not been very closely investigated in that respect). 



With a single exception (Cryptocopc 1 'dringii G. O. S.) all species of which the adult males 

 are known, inhabit comparatively low water, from the beach down to 30 or 50 fathoms. And according 

 to the sexual differences just pointed out the adult males of most genera differ in general aspect and 

 in several characters more from their own females than from males of other genera, and the differ- 

 ences between the two sexes of the same species are most frequently larger than the differences 

 between the female of that species and females of several other genera. The result is that not 

 unfrequeiitly it is impossible with certainty to refer a male to its female, to determine specimens of 

 the male sex. 



While my material of females and immature specimens dealt with in this report is exceedingly 

 large, comprising probably a good deal more than a thousand specimens, I have very few adult 

 males. I establish a new species of Neotanais on a male about twice as long as any male or female 

 hitherto known of this family from any sea. Furthermore, I have 5 males belonging to 3 species of 

 Pseudotanais. 5 males belonging to 3 species of Leptognathia and a male Cryptocopc, in all 11 specimens 

 referred by me to 7 species; the reference of males to five of these species is absolutely certain, but 

 two are referred with a little less certainty. Finally, I have still two males, one of which with a 

 peculiarly armed chela, but being unable to refer them to genus I found it useless to describe them. 

 But this enumeration of 14 adult males as compared with the enormous number of females and 



