>20 "ENDEAVOUR'' SCIENTIFIC RESULTS. 



De Man, 7 together with other significant observa- 

 tions on the species, has called attention to the fact, "that 

 in Para p. rectacutus all the periopods are provided with 

 very small exopods and that there is an epipod on the logs 

 of the 3rd pair.' 7 Porapenceus mcgalops, Smith, also has 

 small, inconspicuous scale-like exopodites on all of the 

 thoracic legs and epipodites on the third and preceding, 

 but not on the last two pairs of legs. As in rectacutus, 

 there are no suture lines in evidence on the carapace. The 

 telson is armed on either side \vith two movable spines 

 in advance of an immovable one ; this is one pair of mov- 

 able spines less than Alcock assigns to his rectacutus, but 

 corresponds to the number de Man (op. cit., p. 82) 

 observed on his "Siboga" specimen of that species. 



The specimens identified as Penwopsis serratus by 

 A. Milne Edwards and Bouvier from the "Blake" 

 collections were all more or less mutilated and included 

 but one male of the typical species, and one of a varietal 

 form. If they were specifically identical with megalopx, 

 either the antennular flagella of these males were 

 wanting, or the secondary male character was over- 

 looked. All the specimens had small scale-like exopodites 

 on the thoracic legs "Tous ces appendices [pattes] sont 

 munis de court . . . [exopodites] en forme d'ecailles 

 qui se reduiseut progressivement de la lere paire a la 

 derniere paire" (op. cit. p. 223). 



The branchial formula given for P. serratus, and said 

 to be common to all representatives of the genus except 

 as regards the number of exopodites, differs from that 

 given by Alcock under "Metapcneus" in having one podo- 

 branch, one arthrobranch and one pleurobranch, instead 

 of one podobranch and two arthrobrauchs on the second 

 maxillipeds, and in omitting mention of the vestigial 

 anterior arthrobrauch found on the penultimate pair of 

 legs of all the "Metapeuei" examined by Alcock. It may 

 not be easy to determine the exact attachment of the two 

 gill plumes of the second maxillipeds, other than the 

 podobrauch, but from a close inspection of /'. tneyalops, 

 I should say that both were arthrobranchs. There is no 

 vestigial anterior arthrobrauch on the penultimate pair 

 of legs. The second maxilliped carries a rudimentary 

 arthrobranch, as noted by Smith in the branchial 



7 Siboga Exped., xxxix.o, Decapoda, pt. i., Penseidse, 1911, p. 78. 



