182 



Gen. 2 Byblis, Boeck, 1870. 

 Syn: Ampelisca, Kroyer (part). 



Body, as a rule, more slender than in the preceding genus, and highly 

 compressed, though scarcely carinated dorsally. Cephalon with the frontal 

 part but little produced, and truncated at the tip, postantennal corner distinct, 

 and nearly right-angled. Anterior pairs of coxal plates much smaller than 

 in Ampelisca; 1st pair scarcely deeper than the succeeding pairs, but con- 

 siderably expanded in their outer part, and densely fringed with slender 

 bristles; 4th pair forming posteriorly a rather projecting acuminate corner, 

 beneath which the edge is evenly curved throughout. Last pair of epimeral 

 plates of metasome not produced at the lateral corners. Urosome short and 

 stout. Corneal lenses, when present, two on each side. Antennae slender, 

 their mutual length different in the different species, basal part of the inferior 

 ones not concealed. Mandibles rather strong, with the body somewhat larger 

 than in Ampelisca, palp very slender, with the 2nd joint not at all expanded, 

 and the last comparatively short. Maxillae about as in that genus. Maxilli- 

 peds with the basal lobe rather narrow and truncated at the tip, masticatory 

 lobe very large, reaching beyond the antepenultimate joint of the palp, penul- 

 timate joint of the latter narrower than in Ampelisca. Gnathopoda very 

 slender, especially the posterior ones, otherwise of much the same structure 

 as in that genus. Anterior pairs of pereiopoda likewise rather similar, except 

 that the carpal joint is comparatively somewhat larger. The 2 succeeding 

 pairs rather slender, basal joint less expanded than in the preceding genus, 

 carpal joint elongated and armed on the outer side with several transverse 

 rows of short spinules, dactylus somewhat stronger than in that genus. Last 

 pair of pereiopoda with the basal joint produced posteriorly to a very large 

 and projecting deflexed lobe, fringed on the anterior and inferior edges with 

 a dense row of short ciliated setaB, inner face of the expansion more or less 

 clothed witli long and slender bristles; outer part of the leg attenuated, 

 propodal joint not at all expanded, sublinear, and more or less spinous on the 

 edges, dactylus extremely narrow, and tipped by 2 unequal bristles. Last 

 pair of uropoda much smaller than in Ampelisca and scarcely reaching beyond 

 the preceding pairs, rami narrowly lanceolate, not setous in female, their 

 opposite edges being more or less distinctly serrated. Telson short and broad, 

 and only slightly incised posteriorly. 



Eemarks. This genus, established by Boeck, is chiefly distinguished 

 from Ampelisca, by the anterior pairs of coxal plates being far less deep, and 

 not concealing the basal part of the inferior antennae, by the form of the 

 mandibular palp and of the last pair of pereiopoda, finally by the rather 



