324 A HISTORY OF EECENT CRUSTACEA 



base, a single central plate issuing between the ' palps * 

 from the fused second joints. The marsupium is like that 

 in Tanais. There are five pairs of pleopods in the male, 

 and five or none in the female. The nropods have both 

 branches two-jointed. 



Typhlotanais, Sars, 1880, is without eyes or ocular 

 lobes. The mandibles have a thick cylindrical molar in the 

 female. In the male the mouth-organs disappear as in 

 Paratanais. The marsupium has the usual four pairs of 

 plates. There are five pairs of pleopods in both sexes. 

 Both branches of the uropods are two-jointed, or one or 

 other of them may be one-jointed. 



Leptognathia, Sars, 1880, has no eyes or ocular lobes. 

 The mandibles are weak, with a feeble pointed molar in 

 the female. The mouth-organs of the male and marsu- 

 pium of the female and the pleopods are as in the preced- 

 ing genus. Of the uropods the inner branch is two- 

 jointed in the female, three-jointed in the male, the outer 

 much smaller, two- or one-jointed, sometimes rudimentary. 



Alaotanais, Norman and Stebbing, 1886, has minute 

 ocular lobes, but no eyes. The mandibles are strong, with 

 large molar, at least in the female, the full-grown male 

 being probably content with the maxillipeds for mouth- 

 organs. The marsupium and pleopods are as in the pre- 

 ceding genus. The first gnathopods are powerful, espe- 

 cially in the male, much like those of Leptochelia. Of the 

 uropods the inner branch is eight- or nine-jointed, the 

 outer two-jointed. 



Neotanais, Beddard, 1886, is no doubt the same genus 

 as the preceding. Both were published by the Zoological 

 Society of London in the same year. The description of 

 Alaotanais was received Nov. 5, 1884, read Dec. 2, 1884, 

 and published in October 1886. Neotanais was, I believe, 

 received and read considerably later, but actually published 

 earlier. Mr. Beddard mentions c mandibles with the usual 

 structure, with a slender extremity and a stout molar 

 process.' His only specimens were males, but not perhaps 

 at the stage when the mandibles would be lost. 



Bathytanais, Beddard, 1886, has distinct ocular lobes, 



