MUSEUM OF COMPARATIVE ZOOLOGY. 61 



flattened a little vertically (or in the direction of the plane of the curvature), 

 and wholly unarmed ; those of the fifth pair reach beyond the tip oi the ros- 

 trum, and the I'ourth and third jiairs are successively a little longer ; the dac- 

 tylus in the fifth pair is a third or a little more than a thiid as long as the 

 propodus, in the fourth pair a little longer than in the fifth, and in the third 

 pair not far from half as long as the propodus. 



The abdomen is evenly rounded and not at all compressed above, and less 

 geniculated at the third segment than in P. Monlaijid. The sixth segment is 

 about once and two thirds as long as the fifth. The telson is about once and a 

 half as long as the sixth segment, and terminates in an acutely triangular tip, 

 armed each side with two long sj)ines, of which the proximal is very much the 

 longer, and at the extreme tip with a few long, plumose setae. 



The branchial formula is the same as in P. Montacjui. 



Pandalus acanthonotus, sp- nov. 



Plate Xni. Figs. 10. 11. 



This species, of which there is but one specimen in the collection, is closely 

 allied to P. tcnuipes, but is at oncg distinguished from it by the deeper and 

 nearly horizontal rostrum with the dorsal teeth forming a continuous series with 

 the spines on the dorsal crest of the carapax ; and by the much longer sixth 

 sonute of the abdomen, which is more than twice as long a? the fifth somite, 

 and longer even than the telson. 



Female. — The carapax including the rostrum is only about a third of the 

 entire length, somewhat contracted in front as seen from al)Ove, and with the 

 rostral carina extending back to about the middle, but not sharp except in front, 

 where it is armed with five slender spines movahbj arlicnlated with the carapax 

 and closely crowded together. The rostrum is considerably shorter than the cara- 

 pax proper, nearly horizontal, expanded below, tapers to an acute ti]>, is armed 

 above with seven teeth, of which the anterior is very minute and a little way 

 from the tip while posteriorly the teeth become slender and at last spiniforni, 

 almost like the spines of the carapax, with which they form a continuous 

 series ; below, the edge is armed with six teeth, of which the anterior one is 

 minute and situated a little back of the tip. 



The eyes are large, pyriform, and black, and, as well as the antennula) and 

 antenna;, are nearly as in P. (ciiuipes. 



The oral appendages are all very nearly as in P. ienuipes; the propodus in 

 the second maxilliped (PI. XI 11. fig. 11) is, however, a little larger proportion- 

 ally, and the very narrow dactylus articulated along nearly half the length of 

 the mesial edge of the propodus very much as in P. Montagui, while in 

 P. tenuipes the dactylus is about half as long as l)road and articulated with the 

 oblique distal end of the propodus. The external maxillipeds reach a little by 

 the tips of the antennal scales, are almost exactly as in P. tenvipes, ami, as in 

 that species, have well developed exopods half as long as the ischia. The oral 



