CRUSTACEA MALACOSTRACA. II. 



The ehelipeds are somewhat difficult. In Apseudes a cheliped seems to consist of only five 

 joints instead of seven plus claw. Rut the presence of an exopod on the first joint proves that it is 

 the second (according to the earlier morphology), and from a comparison with the second pair of legs it 

 is evident that the long joint preceding the chela has been formed by the complete fusion of two 

 joints; finally, the movable finger of the chela answers to the "claw" in the following legs, thus con- 

 sisting of seventh joint and the real claw. In most genera of Tanaidse the ehelipeds consist of the 

 same five joints as in Apseudes, but in several forms, as in the male of Neotanais giganteus, in Crypto- 

 copc Vbringii and C-arctophylax and above all in Anarthrura (comp. Sars' figures) we find a conspicuous 

 piece developed as a separate plate or (in Anarthrura) a large real joint between the usual "first" 

 joint and the body; this plate or joint is certainly the real first joint which in most forms of the 

 order is feebly or not marked off from the cephalothorax. As the ehelipeds show such tangled 

 morphology I have abstained from applying the counting method when the joints to be described 

 must be indicated. Therefore I use some of the names applied by H. Milne-Edwards to the joints of 

 the legs in Decapoda; whether most of the joints in the legs of Tanaidacea and Decapoda can be 

 considered identical as to morphological value according to their number is another and very difficult 

 question not to be discussed here. The apparently first and very conspicuous joint of the ehelipeds 

 in most forms is named the basal; the real first joint in Anarthrura and the plate marked off in the 

 forms just enumerated is named the coxal joint. The joint beyond the basal is named the ischium, 

 but in most forms it affords no character worth mentioning. The next joint is named the carpus, 

 though morphologically it answers to meros and carpus; in the descriptions of the chela I speak of 

 hand and fingers, the hand going to the insertion of the movable finger. 



F. On generic and specific Characters. 



In this report I establish only three genera, all belonging to the Tanaidse. Two of these are 

 well separated, but the third, founded on a single specimen, was established only because it fits badly 

 in the genera known, though it does not seem to possess any single really good generic character. 

 The big genus Leptognathia is divided into groups, and in the future it will certainly be divided into 

 three or four genera, but I think it better to postpone this splitting up until a good number of 

 unknown forms have been discovered, because the Carcinologist will then be more able to settle the 

 value of several characters, whether they mav be considered of generic or only of specific value. And 

 here we fall in with a difficulty. It is with good reason that Sars laid stress on the mouth-parts in 

 females (and immature males) as affording generic characters and especially on the development of 

 the mandibles and the shape of their molar process, if that is present. But of numerous new species 

 the material is very scanty or even consisting of onlv a single specimen, and in such cases an exam- 

 ination of the mouth-parts was postponed. Furthermore many species are so small, that several 

 Carcinologists dealing with such animals are scarcely able to dissect the mouth-parts in such a way 

 that a good representation of the mandibles can be given. And by the examination of the mouth- 

 parts in various species of Leptognathia I found that two such species as L. subcequalis n. sp. and L. ven- 

 f ralis n. sp., which are rather allied in most characters and may be referred to the same group, show 



The Danish [ngolf-Expedition. ill. ;. 2 



