of the North Atlantic and of North-Western Europe. 641 



of the female. The absence of the grasping organ in Cypridina is remarkable, 

 accompanied as it is in that genus by the presence of sucking-disks on the male 

 antennules; and it would seem to be a reasonable conclusion that whereas in 

 Philomedes, &c., the female is grasped by the prehensile organ of the antennae, 

 she is in the case of Cypridina held by the sucking-disks of the antennules. 



Remarkable modifications are characteristic of the mandibular organ, the palp 

 of which may consist of 2-4 joints. The mandible itself is often furnished with 

 what has been called a " mandibular process." This process in the genus 

 Cypiridina is in the form of a small securiform, entire, setose lobe (PI. LV., fig. 6), 

 and is present in both sexes ; in most other genera the lobe is cleft either almost 

 to the base, or only a little way down (PI. liii., fig. 4). It is remarkable, if it 

 assists in mastication, that a divided liirsute lobe of this kind is present in ? , 

 but not in ^ , in the genus Philomedes, and tliat in the male of this genus the 

 masticating spines, presently to be described, are also absent, while Crossophorus 

 has an exactly similar lobe present in both sexes. Rutiderma ? , Paramekodon ? , 

 and Tetragonodon ? , are furnished with a cleft process, but in Sarsiella ? it is 

 altogether absent. The first joint of the palp in all cases where the basal joint 

 is furnished with a masticating process, bears on its lower margin " masticating 

 spines," which are of peculiar and varied structure in different genera (PI. liii., 

 fig. 4 a). The extremity of this joint above has usually a small laminar 

 appendage ; the two final joints vary greatly, and afford good generic character. 

 In Cypridina the penultimate joint is long, about equalling the two preceding 

 joints, gradually attenuating from the base to tlie extremity, and densely 

 setose above. In Crossophorus, Philomedes, and Tetragonodon, the joint is also 

 long and densely setose above, but scarcely attenuated. In the precedmg 

 genera the last joint ends in several setae and two or more ungues of moderate 

 length. In Paramekodon the penultimate joint is also very long, with a dense 

 fascicle of seta on the upper margin, and the limb terminates in a slender curved 

 unguis of remarkable length. In Nematohamma and Sarsiella (PI. lx., fig. 10) 

 the penultimate joint is very short, less or not more than half the length of the 

 preceding. In the former genus it bears only one large, annulated seta on the 

 upper, and one similar seta on the lower margin, and the limb ends in a single 

 large unguis, but no setae, the unguis nearly equalling in length the last three 

 joints. In the latter genus there are no setse on the three terminal joints, each of 

 which supports an unguis, which in consequence of the extreme shortness of the 

 last joints are brought close together, each uiaguis being successively longer than 

 tlie preceding. Lastly, Rutiderma possesses a limb of entii'ely different structure 

 (PI. LViii., fig. 14) ; the last three joints are coalesced into a joint of extraordinary 

 massiveness, which gives support at its extremity to a large cliela, the finger 



