MAHEIAGE CUSTOMS 327 



supposed that in Tanais duhim, Kroyer, there were two 

 forms of the male, but Sars considers that of the two 

 supposed forms one is Leptochelia dvhia and the other 

 Heterotanais anomalus, Sars. He has not found any true 

 dimorphism in the males of any of the Tanaidae. The 

 distinction between Leptoclielia Savignyi and Leptochelia 

 dubia is itself open to some doubt. M. E. Ohevreux has 

 sent me specimens from Villefranche, the males of which 

 have gnathopods, such as Kroyer attributes to the 

 Edwardsii and Sars to the Savignyi form, that is, with the 

 teeth on the thumb very wide apart, but on the other 

 hand they have the first antennas, such as Sars attributes 

 to the dubia form, with a curve at the base of the first 

 joint, and with a flagellum, not indeed of nine joints, but 

 of eight. These antenn® agree with Kroyer's description 

 of Edwardsii and also with the figure and description by 

 Bate and Westwood, so that, unless Sars has himself for 

 once made a confusion, the males of dubia and Savignyi 

 would seem to be undistinguishable in regard to the first 

 antennas, not necessarily at every stage of existence, but 

 at some stage. Since the marital Tanaid frequently 

 sacrifices his mouth-organs to the enormous develop- 

 ment of his chelipeds, he must, as Norman observes, 

 either reacquire his feeding apparatus at a subsequent 

 moult, or else die of inanition. The alternation of form 

 in the same individual is not improbable. It is, of course, 

 quite distinct from dimorphism. To Heterotanais Sars 

 assigns the American species Leptochelia limicola, Harger, 

 and the New Zealand Paratanais tenuis, Thomson, and 

 with Heterotanais Orstedi (Kroyer) he identifies Tanais 

 curculio, Kroyer, (? , Tanais halticus, Fritz Miiller, ? , and 

 Tanais rhynchites, Fritz Miiller, J. The species which 

 Bate and Westwood call Paratanais forcipatus (Lilljeborg) 

 should be named Paratanais Baiei, Sars, and their Paro/- 

 tanais rigidus has now become Leptognathia rigida (Bate 

 and Westwood). Leptognathia laticaudata, Sars, has been 

 recently taken in the Clyde, and Leptognathia Lilljeboi'gi, 

 Stebbing, is found in North Devon. The deep-sea species, 

 Alaotanais (or Neotanais) serratisp)inosus and Alaotanais (or 



