226 STALK-EYED CRUSTACEA. 



Hanscnomf/sk and Ceratomysis, being furnished with exopods and internal 

 meral lobes. 



PetalopMhalmits, Scolophthalmus, Hansenomysis, and Ceratomysis, form a 

 natural group of genera characterized by the development of seven pairs 

 of incubatory lamelliB in the female (the anterior pair sometimes rudimen- 

 tary), the absence of an exopod from the maxillipeds, the outgrowth of a 

 large, porrect lobe from the inner margin of the merus of the gnathopods, 

 and the imperfect development of the carapace, which leaves the last two 

 segments of the cephalo-thorax free. This group is connected with the more 

 normal genera of Mysidoe, through the genus Boreomym, in which the incu- 

 batory pouch is likewise composed of seven pairs of lamellae, but the maxil- 

 lipeds are furnished with an exopod, the gnathopods lack the internal meral 

 lobe, and the carapace covers all the thoracic segments. The maxillipeds 

 have an internal meral lobe in PetalojMhalmus, Cemtomysis, and Borcomysis ; 

 the gnathopoda are furnished with an exopod in all the genera excepting 

 Pefaloplilhahnus. Petalophthahnus differs from all the other genera here men- 

 tioned in the absence of an exopod from the gnathopods and in the enormous 

 development of the mandibular palps. In the great size of the antennn- 

 lar peduncle as compared with the second antennae, SeolopMhalmus exhibits 

 special affinity with VeUdopMliahnus. 



Scolophthalmus lucifugus Fax. 

 Plate LV., Fig. 1-P. 



Bull. Mus. Comp. Zool., XXIV. 219, 1893- 



Rostrnm long, acute ; antero-lateral margins of carapace oblique, armed 

 with two spines, one behind the external side of the antennule, the other 

 at the antero-inferior angle ; posterior lateral wings short and rounded. 

 Abdominal segments smooth and subcylindrical, sixth segment nearly as 

 long as the two antecedent segments combined. 



Length, 42 mm. 



Station 3400. 1322 fathoms. 1 fem. 



