29 



Gen. 9. EctillOSOma, Boeck, 1864. 



Generic Characters. Body more or less slender, pronouncedly fusiform 

 in shape, with the anterior division scarcely broader than the posterior. Ce- 

 phalic segment gradually attenuated in front, and produced to a tongue-shaped 

 hyaline rostral plate, arching over the bases of the anterior antennae; lateral parts 

 not very deep, almost wholly exposing the oral appendages. Epimeral plates of 

 the 3 succeeding segments acute-angular behind. Last segment of metasome scarcely 

 narrower than the preceding segment. Urosome gradually attenuated behind, 

 genital segment without any trace of a transversal suture in the middle, last 

 segment rather small and more or less deeply cleft. Caudal rami comparatively 

 short, diverging, the 2 middle apical setse closely juxtaposed and considerably 

 thickened at the base. Anterior antennae rather small, 5 7-articulate, and clothed 

 with slender setse. Posterior antennae with the outer 2 joints confluent, outer 

 ramus much more slender than the inner, and distinctly 3-articulate. Anterior lip 

 compressed and more generally projecting in front to an acute recurved point. 

 Mandibles sharply curved, with ihe masticatory part deeply cleft and armed with 

 a limited number of simple teeth, outside which is attached a thickish seta; palp 

 comparatively large, with the basal part much elongated, both rami uniarticulate, 

 the inner one abruptly recurved and tipped with long setae, outer ramus compara- 

 tively small. Maxillae with the masticatory part armed with 3 or 4 strong, claw- 

 like spines, palp divided into several setiferous lobes. Anterior maxillipeds con- 

 sisting of 2 thickish basal joints, very movably articulated the one to the other, 

 terminal part rudimentary, carrying 2 slender, claw-like spines curved anteriorly. 

 Posterior maxillipeds issuing inside the anterior, slender, straight, 3-articulate, 

 middle joint narrow and elongated, terminal joint small, tri-setose. First pair of 

 natatory legs scarcely smaller than the others, with the inner ramus longer than 

 the outer. Last pair of legs closely approximate, and each consisting of 2 well- 

 defined joints, the proximal one forming inside a large lamellar expansion carrying 

 2 spiniform setae, distal joint trilobate, each lobe tipped with a similar seta. 



Remarks. This genus was established in the year 1864 by Boeck, to 

 include 3 Norwegian species, one of which, E. melaniceps, is perhaps identical 

 with the form recorded by Baird as Canthocamptus minuticornis (Miiller). Subse- 

 quently several new species have been added, chiefly by Prof. Brady and Th. Scott. 

 The latter author, in his interesting Revision of the British Species of the Genera 

 Bradya and Ectinosoma, records no less than 13 different species belonging to 

 the present genus, and nearly the same number have been observed by myself off 



