MARRIAGE CUSTOMS B27 
supposed that in Tanais dubius, Kriyer, 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 Tanaide. 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 Krdéyer attributes to the 
Hdwardsii 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 antenne. 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 antenne agree with Kréyer’s description 
of Hdwardsi 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 
antenne, 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 balticus, Fritz Miller, 2, and 
L'anais ‘rhynchites, Fritz Miller, ¢. The species which 
Bate and Westwood call Paratanais forcipatus (Lilljeborg) 
should be named Paratanais Batei, Sars, and their Para- 
tanais rigidus has now become Leptoqnathia rigida (Bate 
and Westwood). Leptognathia laticaudata, Sars, has been 
recently taken in the Clyde, and Leptognathia Lalljeborgi, 
Stebbing, is found in North Devon. The deep-sea species, 
Alactanais (or Neotanais) serratispinosus and Alaotanais (or 
