GAMMARIDEA. 833 



mediocres. Epimerae anteriores obsoletae. [An styli caudales 3tii simplicis- 

 simi ?] 



Subfam. 3. ICILIN^. — Antennae non pediformes nee subpediformes, 

 flagellis sat longis basique sat brevi instructaa. Styli caudales ac in 

 Corophinis. 



Gr. 1. Icilius, Dana. — Pedes toti unguiculati et tenues, 4 antici longi, non pre- 

 hensiles, ciliati, 10 postici fere similes. Antennas superiores breviores, non ap- 

 pend iculatae. 



G. 2. Pterygocera, Latr. — Pedes posteriores sublaniellati. Antennas superiores 

 breviores, appendiculatae, inferiores basi dilatatae. 



Subfamily CLYD0NIO3. 



The Clydonia group is aberrant in most of its characters, as will be 

 observed in the following descriptions and the illustrating figures. 

 The caudal stylets are unlike any others in the Gammaridea. The 

 antennae are also anomalous. Only two were observed, and these 

 were long, straight, stout, rigid organs, lying side by side, and except- 

 ing the basal joints, hardly articulated, or only indistinctly so. The 

 legs are very long, and filiform ; the fifth pair is much the longest, 

 and from the fifth to the seventh the decrease in length is very rapid, 

 the seventh being short. These legs appear to be used for standing ; 

 and, as the fifth pair is the longest, they are fitted to place the body 

 in a horizontal position rather than in the erect posture, observed in 

 the Caprellids and Arcturi. The claw, moreover, is exceedingly 

 short. 



The body is narrow, with very small or obsolescent epimerals. 

 The abdomen has the usual number of segments, as also the thorax. 

 The eyes are small. The specimens are not in our collections, and 

 we are not, therefore, able to add more details to what are given in 

 our original descriptions and figures, made in 1838 and 1839, when 

 the specimens were taken. The following genus is the only one 

 detected. 



and many other characters of Erichthonius, but with the epimerals of the anterior tho- 

 racic segments of considerable size j and, moreover, no gressorial habits were observed. 

 They are, therefore, with some hesitation, arranged in a genus named Pyctilus, among 

 the G-ammaridae, subfamily Gammarinae. 



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