222 STALK-EYED CRUSTACEA. 



agrees with the male of P. armiger, barring the usual sexual peculiarities of 

 an incubatory pouch and simple caudal limbs. The mandibular palpus and 

 carapace have the same form and proportions as in the male. The telson, 

 moreover, is truncate and entire, and the maxillipeds and gnathopods are 

 devoid of exopods — features that Willemoes-Suhm thought were character- 

 istic of the male. The brood-pouch of the '' Blake " specimen consists of 

 six pairs of incubatory lamella) and the rudiments of a seventh pair between 

 the bases of the first pair of legs or gnathopods. From the posterior side 

 of the base of the lamelloa of the posterior pair there springs a curled and 

 ciliated lobe. This specimen, which is represented on Plate LIII., is prob- 

 ably the female of PetalopUlialmiis armiger, or at any rate of a closely related 

 specie.s.* The specimen that Suhm took for the female of P. armiger is 

 clearly a Boreomysis, probably B. sci/phops G. 0. Sars, as Hansen t maintains. 



Suhm and Sars both represent the carapace of the male P. armiger with- 

 out lateral wings, the postero-lateral angles being obliquely truncated. But 

 Sars explains this feature in his text (p. 175) as due to a folding of the cara- 

 pace. In the female specimen from the " Blake " dredgings the carapace is 

 produced posteriorly so as to form short, rounded lateral wings, just as in 

 P. pacificus. 



According to Sars, the flagellum of the second antennfe is imperfectly 

 developed in the type specimen of P. armiger, consisting merely of a biar- 

 ticulate pednncle, the terminal portion being absent. This defect is without 

 doubt due to mutilation of the type specimen, for in the " Blake " specimen 

 of P. armiger (female), and also in the specimen o? P. pacificus (male) secured 

 during the cruise of the " Albatross," the terminal portion of the flagellum is 

 present as a slender lash about equal in length to tlie terminal segment of 

 the peduncle, and composed of about six segments.:}: 



The epipods of the maxillipeds, which Sars did not detect in the tj^pe of 

 P. armiger, are plainly visible in the two specimens of P. armiger and P. pa- 

 cificus now before me. They consist of delicate long appendages attached to 

 the basal segment of the maxillipeds, and tucked away under the sides of 

 the carapace. 



In the light afforded by the " Blake " specimen of P. armiger, it be- 



• The telson of the "Blake" female (Plate LIII. Fif^. 2") difTers somewhat fmm the telson of the male 

 P. armijer, inasmuch as it narrows posteriorly and is furnished with but seven seta; on the posterior margin. 

 One of these sette (tlie shortest) is in the median line, the others form three pairs, the external ones twice the 

 length of the next pair inside. 



t Vidensk. Mcddelelser fra den nalurhist. Forening i Kjoljcnhavn for Aarct 1887, p 212, 1888. 



X Plate LIII. Fii,'. 2\ Plate LIV. Fig. V. 



