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PETALOPHTHALMUS. 



221 



The specimen from Station 2619 (Plate K, Fig. 2) is apparently a young 

 female. It was caught in the Tanner net which had been towed at a depth 

 of 1000 fathoms (100 to 400 fathoms above the bottom)^ and drawn up 

 closed. 



Family MYSIDiE. 



PETALOPHTHALMUS W.-Suiim. 



Zcitsclir. wlasenscb. ZooL, Vol. XXIV.j p. xiv, 1874; Trans. Linn. Soc. London^ 2d Ser., Zool.jl. 43, 1875. 



(In part : so far as relates to tlic male.) 



In the abovc-^citcd papers Willcmocs-Suhin described as male and female 

 of the same species Pelalophlhalmns armiger, two interesting Atlantic Schizo- 

 pods from the "Challenger" Expedition characterized by the atrophy of 

 the eye and the conversion of the eye-stalk into a leaf-like plate. The 

 male differed in a singnlar manner from the female in the form of the 

 carapace, antenna), mandibles, maxillipeds, gnathopods, telson, etc. In the 



I 



former the carapace was short, leaving the two posterior thoracic segments 

 exposed; the second pair of antennae lacked the flagellum ; the mandibular 

 palps were enormously developed, forming a pair of very powerful prehensile 

 limbs reaching far beyond the peduncle of the first pair of antennas; the 

 maxillipeds and the gnathopods were devoid of exopods ; the telson was 



> 



truncate and entire at the distal end. In the female, on the other hand, the 

 carapace covered the posterior part of the thorax, the telson was deeply 

 incised, and the appendages presented the normal form. There were seven 

 pairs of incubatory lamella) under the thorax, as in Boreomysu G. 0. Sars, 

 to which genus the specimen conformed in most regards. When the " Chal- 

 lenger '' Schizopods were afterwards placed in Professor Sars's hands, the 

 female of '^ relalopJdhalmus armiger'" had been lost, so that no further account 

 of the specimen was published. The male was redescribed and figured by 

 Sars with great care.* 



In the "Albatross'' collection of 1891,1 find one male specimen agreeing 

 in all the essential structural features with the male 

 Suhm, but diflering in some trivial characters of merely specific value. This 



mm anmgcr 



ifu 



Wh 



during tlie cruise of the "Blake" in 1877-78, a female Scliizopod, 33 mm. 

 long (Station 29, lat. 24° 36' N., long. 84° 5' W., 955 fathoms) that closely 



* 



Rep. Clialleugcr Scliizopoda, pp. 174-177, Bate XXXII. Fig. 1-9. 



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