No. 26.] ARTHROSTRACA OF CONNECTICUT. 45 



and tumid, with large, compound eyes which cover nearly the 

 whole side of the head ; gills on three or four thoracic segments ; 

 last two abdominal segments fused, uropods usually with laminate 

 rami, forming a tail fan. Hepato-pancreatic tubes two or none, 

 rectal gland wanting ; heart with two pairs of ostia, rarely three. 

 Exclusively pelagic in habitat. 



Hyperia Latreille. 



Antennae in female very small, subequal. 



Mandibles with molar tubercle large, palp of moderate size 

 with the second and third joints subequal in length. First max- 

 illae with palp not greatly expanded, inner corner produced to a 

 tooth-like projection. Maxillipeds with outer plates obtuccly 

 pointed, inner margin with small tufts of setae. 



Gnathopods scarcely chelate; .carpus produced ventrally, 

 especially in second pair. Pereiopods comparatively short, robust, 

 and subequal in length. Uropods broad, with foliaceous rami. 

 Telson large. 



Hyperia galba (Montagu), 



1813. Cancer Gammarus galba, Montagu, Trans. Linn. Soc. 

 London, vol. 11, p. 4, pi. 2, fig. 2. 



1890. Hyperia galba, G. O. Sars. Crust. Norway, vol. i, 

 p. 7, pis. 2 and 3, fig. I. 



Head much deeper than long, with reniform eyes covering 

 whole lateral aspect ; back strongly arched. 



Antennae in female very short, subequal. Mandibles with 

 long, slender three- jointed palp. 



Gnathopods small, scarcely chelate, and with only a few 

 bristles ; first pair with carpus having postero-distal angle ex- 

 panded somewhat to form an acutely triangular lobe which is 

 provided with a few setae ; propodus oblong, slender, with poste- 

 rior margin finely serrate ; dactyl small. Second pair with carpus 

 greatly produced at posterior apex, forming a slender triangular 

 lobe which reaches beyond the middle of the propodus ; the 

 latter quite similar to that of the first gnathopod. 



Pereiopods subequal in length, robust, and almost devoid of 

 setae ; coxal plates small ; basal joint of each stout. 



Last two abdominal segments fused; uropods broad, with 

 foliaceous rami ; second pair not extending as far as the first ; ter- 



