268 A HISTORY OF EECENT CRUSTACEA 



unabashed author himself remarks that ' this genua was 

 instituted by Mr. Leach, who has derived the name from 

 the English word prawn.' He assigned to it the species 

 flexuosiis, Miiller, and integer, Leach. 



Petalophthalmus was so called from having the eyes 

 leaf-like. They are described in the single species, Petal- 

 oplithahnus armiger, as ' quite rudimentary, without any 

 trace either of pigment or visual elements, constituting 

 merely two thin and pellucid lamellae, of an oblong form, 

 and mounted on very short and narrow pedicles.' The 

 species was obtained in the tropical Atlantic from a depth 

 (jf 2,500 fathoms. The telson is not incised at the apex. 

 The male is distinguished by the astonishing and perhaps 

 unique development of the mandibular ' palp,' and by the 

 lamellar prolongation of the fourth joint in the first and 

 second maxillipeds, the first pair being, contrary to the 

 custom in this family, devoid of exopod and epipod. A 

 female with seven pairs of marsupial plates has been, per- 

 haps incorrectly, assigned to this species. 



For the preoccupied Ardomysis, Hansen, I propose the 

 name Hansenomysis. It has a short carapace, the mandi- 

 bles with prominent cutting edge, long molar tubercle, 

 and very large ' palp,' the first maxillipeds without 

 exopod, and with none of the joints expanded, but with an 

 epipod, the second maxillipeds with a small ovigerous plate 

 at the base, and the short fourth joint expanded into a 

 large plate. The three following pairs of appendages are 

 very slender, with a short hairy terminal joint, and there 

 is a very long, sharp, bare nail on the next three pairs. 

 Hansen considers that his Hansenomysis Fyllce and the 

 male of v. Willemoes Suhm's Petalophthalmus armiger 

 might form a separate family in the Schtzopoda, The sup- 

 posed female of the latter species he regards as belonging 

 to Boreomysis scyphops and not to Petalophthalmus. 



Boreomysis, of which the type species is Boreomysis 

 arctica (Kroyer), taken off the coasts of Greenland and 

 Norway, includes among others Boreomysis scyphops, Sars, 

 which is far from being only a boreal Mysis. It was ia 

 fact first met with by the Ghallenfjer at great depths in the 



