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supposed that in Tanais dubius, Kroyer, there were two 

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

 supposed forms one is Leptochelia dubia and the other 

 Heterotanais anomalus, Sars. He has not found any true 

 dimorphism in the males of any of the Tanaidse. The 

 distinction between Leptochelia Savignyi and Leptochelia 

 dubia is itself open to some doubt. M. E. Chevreux 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 d Libia form, with a curve at the base of the first 

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

 of eight. These antennas 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 tennis, Thomson, and 

 with Heterotanais Orstedi (Kroyer) he identifies Tanais 

 curculio, Kroyer, $ , Tanais balticus, Fritz Miiller, ? , and 

 Tanais rhynchites, Fritz Mtiller, <$ . The species which 

 Bate and Westwood call Paratanais forcipatus (Lilljeborg) 

 should be named Paratanais Batei, Sars, and their Para- 

 tanais rigidus has now become Leptognathia rigid a (Bate 

 and Westwood). Leptognathia laticaudata, Sars, has been 

 recently taken in the Clyde, and Leptognathia Lilljeborgi, 

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

 Alaotanais (or Neotanais) serratispinosns and Alaotanais (or 



