222 DR. W. T. CALMAlSr ON APHAREOCAEIS, 



This is practically the formula given by S.I. Smith for Sergestes japonicusy. 

 Sp. Bate (S. mollis, Smith), but the branchia, and especially those of the 

 penultimate somite, are much larger than in that species and, of the vestigial 

 branchiae, the posterior two at any rate show a certain amount of lobulation. 



Abilities. — The genus Aphareocaris resembles Sergestes in the following, 

 among other less important characters : — 



(1) The reduction of the branchial system, and the insertion on the body- 



wall of those branchiae which correspond to the arthrobranchi?e of 

 the Penseidse, 



(2) The absence of exopodites from all the thoracic limbs except the first 



maxillipeds. 



(3) The form of the second and third maxillipeds and particularly the 



subdivision of the two distal segments of the latter, 



(4) The flattened form and long marginal setai of the last two pairs 



of legs. 

 It differs from Sergestes and the other Sergestida^, and resembles the 

 Pengeidse, in the following points : — 



(1) The first three pairs of legs are chelate and none of their segments are 



subdivided. 



(2) The last two pairs of legs possess the full number of seven segments. 



(3) The autennule of the male is without a prehensile apparatus. 



These resemblances to the Penseidfe are all of a general character, serving 

 to indicate the primitive position of Aphareocaris with respect to the more 

 specialized genera of Sergestida?, but not in any way counterbalancing the 

 important and positive characters by which it is linked to that family. 

 It seems, therefore, that Nobili was justified in his suggestion that the genus 

 should be placed among the Sergestida?. Of an affinity with the Stenopidea,' 

 as suggested by Mr, Stebbing, I can find no evidence. 



Specific characters. — Paulson's specimen may be presumed to have been 

 a female, since he makes no mention of a petasma. It is, therefore, a matter 

 of analogy and conjecture whether the differences from the specimen now 

 described are individual, sexual, or specific. There seems a reasonable 

 probability, however, that some at least of the following belong to the last 

 category. 



Rostral crest with one tooth. Penultimate segment of third 

 maxilliped divided into four parts. Chela of third leg not more 

 slender than that of second, about six times as long as wide, and 

 less than two-thirds as long as carpus . A. ine^'inis (Paulson), Red Sea. 

 Rostral crest with two teeth. Penultimate segment of third 

 maxilliped divided into three parts. Chela of third leg much 

 more slender than that of second, at least ten times as long as 

 wide, and nearly three-fourths as long as carpus. 



A. elegans, sp. n., Torres Straits.. 



