102 



The last three pairs of legs are moderately stout and not very long : the 

 3rd pair, which are the longest, reach beyond the external maxillipeds by their 

 dactylus ; the 5th pair, which are the shortest, do not reach the end of the 

 carpus of the 1st pair. In the 3rd and 4th pairs the posterior border of the 

 merus is spinose. 



In the Investigator collection are two males and an egg-laden female, from 

 the Andaman Sea, 185 fathoms. 



In comparing our specimens with Milne Edwards' figure, the only obvious 

 difference is that in the former the pleura of the 5th and 6th abdominal somites 

 have their postero-inferior angles acutely produced, as in all the species of 

 Pandalus with which I am acquainted; and not rounded off, as in the figure. 



, AT 2126-2128 



Regd. Nos. ^ . 



HETEROCARPUS, A. Milne Edwards. 



Heterocarput, A. Milne Edwards, Ann. Sci. Nat., Zool., (6) XI. 1881, Art. 4, p. 6 : Spence Bate, Challenger 

 Crust. Macrura, p. 627. 



As Pandalus, with the following points of exception : 



The integument is hard and rigid : in addition to the median (post-rostral) 

 crest, which is very long and strong, there are lateral longitudinal crests on the 

 carapace : there is no ocellus at the margin of the eye. 



As in some species of Plesionika, the legs of the 2nd pair are remarkably 

 unequal. 



In all the Indian species the external maxillipeds have a small exopodite, 

 and epipodites are present on all the thoracic legs except the last ; and in all, 

 the scaphognathite is short, broad, and rounded. 



The branchial formula is exactly the same as that of Pandalus. That is 

 to say, there are epipodites on the appendages of the first 7 thoracic somites, 

 a podobranch on the 2nd maxillipeds, two arthrobranchs on the external 

 maxillipeds and one on each of the next four somites, and a pleurobranch on 

 each of the last five thoracic somites in all, 12 branchiae and 7 epipodites on 

 either side. 



The crests of the carapace have been described by Faxon, in Mem. Mus. 

 Comp. Zool. XVIII. 1895, p. 149. "When fully developed there are, besides the 

 median (post-rostral) crest, and besides the fine lateral marginal crest, three 

 carinae on either side. 



The first, or " post-ocular " carina, which is the most constant and usually 

 the best developed, runs from the middle of the orbital notch to the posterior 

 border of the carapace : it may sometimes be deficient in its anterior two-thirds, 

 or absent altogether. 



