MUSEUM OF COMPAKATIVE ZOOLOGY. 71 



which extends to the base of the rostrum ; and the anterior margin is armed 

 as in M. Agassizii. The rostrum is considerably longer than the carapax 

 proper, very slender, directed slightly downward for a short distance from the 

 base, and is then nearly horizontal to the very slender and acute tip ; is armed 

 above for its whole length with fourteen teeth, of which the four or five pos- 

 terior are nearer together than the others, and the two posterior very small and 

 back of the orbit on the carapax proper ; and is armed below with nine teeth 

 from in front of the eye to the tip. 



The eyes are very much larger than in M. Agassizii, pyriform, and black. 

 The antennulse are very nearly as in M. Agassizii, but the thickened proximal 

 part of the outer or major flagellum is relatively a little shorter. The anten- 

 nal scale is about half as long as the rostrum, about three fourths as long as 

 the carapax excluding the rostrum, and of nearly the same form as in M. 

 Agassizii. 



The labrum and metastome are nearly as in M. Agassizii. The mandibles 

 differ from those of M. Agassizii in the molar areas being very small, nearly 

 obsolete, and not distinctly separated from the ventral process, which is armed 

 with teeth more uniform in size and not becoming rudimentary anteriorly. 

 The terminal segment of the mandibular palpus is slightly shorter than in 

 M. Agassizii, but in other respects the palpus does not differ. The distal lobe of 

 the protognath of the first maxilla is very broad at the prehensile edge, and the 

 lobe is much larger than the proximal lobe ; the endopod is more slender than 

 in M. Agassizii, is armed with one in place of two spines on the fold near the 

 distal extremity, and is without marginal seta?. The divisions of the distaL 

 lobe of the protognath of the second maxilla are much broader distally, pre- 

 senting much longer prehensile edges, and the scaphognath is narrower than in 

 M. Agassizii. The protopod of the first maxilliped is as in M. Agassizii, but 

 the exopod and endopod (PL XII. fig. 10) differ conspicuously. The endopod 

 is more slender and the distal segment is very much shorter, while the lamel- 

 liform exopod has the inner angle of the distal extremity prolonged and indis- 

 tinctly segmented, thus approximating to the early stages, in which it is 

 doubtless ftagelliform. The second maxilliped is as in M. Agassizii, except the 

 terminal portion of the endopod (PL XL fig. 4 d ) which differs in the same way 

 as that of Pandalus tenuipes differs from that of P. acanthonotus (PL XIII. 

 figs. 11, 12), but to a greater extent, the dactylus being narrow, longer than 

 broad, and transversely articulated with the propodus. 



The external maxillipeds and chelate legs are almost exactly as in M. Agas- 

 sizii. The third and fourth pairs of legs are alike, and differ from those of 

 M. Agassizii in having shorter carpi scarcely half as long as the meri, propodi 

 about twice as long as the carpi, and dactyli only a very little shorter than the 

 propodi, slender, slightly curved, and armed with a few minute spines. The 

 posterior legs are scarcely three fourths as long as the fourth, but the segments 

 have nearly the same relative proportions except the dactylus (PL XI. fig. 4*), 

 which is about a third as long as the propodus, obtuse at the tip, and armed 

 along the lower edge and at the tip with serrate setae, of which the terminal 



