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226 



STALK-EYED CRUSTACEA. 



Ilansenomym and Ceratomysis, being- furnished with exopods and internal 

 meral lobes. 



PetalopfdhalmuSy ScolophlJialmiis, Hansenomy sis ^ an d Cer atomy sis ^ form a 

 natural group of genera characterized bj the development of seven pairs 

 of incubatory lamell99 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 Mysidm through the genus BoreomysiSj in which the incu- 

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

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

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

 have an internal meral lobe in P etalophllialmus ^ Ceralomysis^ and B or corny sis ; 

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

 P elahpUhalmiis . P etalophthalmiis differs from all the other genera here men- 



r 



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 antennu- 

 lar peduncle as compared with the second antennae, Scolophthalmus exhibits 

 special affinity with PelalopMhalmus. 



N 



Scolophthalmus lucifugus Eax. 



Plate LV., Fig. 1~1\ 



Bull. Mas. Comp. Zool., XXTV. 219, 1893- 



Rostrum 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 combmed. 



Length, 42 mm. 



Station 3400. 1322 fathoms. 1 fern. 





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