CRUSTACEA FROM THE 'CHALLENGER' EXPEDITION. 27 



entirely lost its flattened form, and is a sort of leg, which, however, like the main branch, 

 is not jointed, but is densely covered with hairs on one side. When comparing such a foot 

 with the pereiopod of a true Schizopod, as, for example, Lopliogaster (Sars, Beskrivelse 

 over Lopliogaster typicus, tab. ii. fig. 35), we see in both on the basal joint the bran- 

 chial appendages, which in Nebalia longipes are very simple, and in Lopliogaster divided 

 and arborescent. Erom the second joint starts the palpus, which in our case has a 

 different shape from that of Lopliogaster, but which morphologically is the same thing. 

 In the foot itself we find in Lopliogaster well-defined joints and a terminating claw, in 

 N. Geoffroyi we still find the joints, but in our case we find no joints; in all three, how- 

 ever, it is not difficult to find out the corresponding parts. 



The first four pairs of abdominal feet or pleopods (fig. 11) have a large basal joint den- 

 ticulated exteriorly, to which two rami are attached, the interior of which is longer and 

 has at its base a little appendage, which is by means of a denticulation at the top united 

 to a similar one of the other pleopod. It has been called by Claus, who found it in N. 

 Geoffroyi, the retinaculum. Such appendages have been shown by Claus also in Stoma- 

 topods, and figured by Milne-Edwards from the Decapod genus Atya. The fifth and 

 sixth pair of pleopods resemble very much those in N. Geoffroyi. 



The two joints of the/urea are covered at the top with tufts of long and dense hairs. 



Among twenty to twenty-five females I discovered two or three males, easily recogni- 

 zable by their minute size and the enlarged flagellum of the anterior antenna?, which here 

 are transformed into real prehensile organs. The males are only 3 millims. long, and 

 differ from the females also by being more slender, by their shorter pleopods and their 

 antennae, which are on the whole somewhat shorter and bigger. The pectoral feet are 

 exactly the same as in the females. In the males of N. Geoffroyi the second pair of 

 antennae have an enormously long flagellunii something like the Cuma male ; while in our 

 Nebalia the second antenna differs very little from that of the female, nor are the olfac- 

 tory hairs to be seen in much greater quantity, unless perhaps at the top and the outer 

 edge of the third joint. The first antenna (fig. 6), however, is very different in the male ; 

 for its squamiform flagellum is greatly swollen up, and the joints are only to be discerned 

 as small protuberances with some hairs on them on one side. This conformation is 

 rather a phyllopodal one — so far as I can make out here, something like that found in 

 Estheria. 



I found, like Claus, a ductus ejaculatorius directed towards the base of the eighth 

 pereiopod, but could not exactly see its opening. 



This Nebalia differs from the two species hitherto known, by the spines on the upper 

 surface of its eyes, by the tuft of hairs at the top of the furca, by the form of its legs, in 

 which the phyllopodal character has been nearly entirely lost, and the schizopodal cha- 

 racter has been more approached than in any other species of this genus. In the male, 

 however, characters have been found which are wanting in the male of N. Geoffroyi. We 

 see a modification of the first antenna reminding us of Estheria, but no prehensile organs 

 on any of the feet. This species therefore approaches, so far as the shape of its legs is 

 concerned, the higher Crustacea more than N. Geoffroyi ; but the prehensile organs of 

 its male are characters which show, again, that there remains a good deal of phyllopodal 



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