4 Cumacea 



intestinal canal with the anal opening in the telson, or in the 

 equivalent portion of the telsonic segment, when the telson itself 

 is in fusion with the sixth segment of the pleon; hepatopan- 

 creatic glands situated below the stomach form from one to four 

 pairs of lobes; the nerve chain has a dorsal cephalic ganglion 

 followed ventrally by ten well developed ganglia and six caudal 

 ganglia of which all but the lastare very slight, the whole series 

 connected by double commissures. Ovaries and testes paired. 

 Development of young carried far forward within the body of 

 the mother. 



Integument calcified, more or less brittle. The carapace usually has 

 a bell-shaped frontal lobe, with small, often eyeless, eyelobe at its apex, both 

 enclosed by a pair of pseudorostral lobes drawn round from the sides to 

 meet in front; the inferolateral margins fold underneath, leaving a space 

 which is occupied by the third pair of maxillipeds except for a narrow opening 

 on either side to admit water into the branchial cavities; when the epipods 

 of the tirst maxillipeds, commonly furnished more or less with branchial leaflets, 

 have been sufticiently irrigated, the pair of exopods in combination, in 

 coalescence, or separately and apart shoot forward to leave room for the 

 water to pass out in front, and are then withdrawn to close the openings 

 till a fresh supply has been made use of, this respiratory arrangement being 

 apparently found only in this Order of Crustacea. The fifth pedigerous 

 segment is narrower than the rest, its appendages more or less late in 

 development, and sometimes, it appears, permanently wanting. The narrow 

 pleon is always without pleopods in the female. The telson, to which the 

 anal aperture belongs, is often fused with the preceding segment, the term 

 telsonic segment being applied to the resulting compartment. 



Eyes may be entirely wanting, or only represented by pigment, or 

 efficient with corneal lenses varying in number from 2 or 3 to 11; the 

 lenses of the single eye are usually but not always in close proximity; eyes 

 distinctly paired are rare. First antennae never elongate, the peduncle 

 three-jointed, often stouter in male than in female, principal flagellum scarce- 

 ly ever as long as the peduncle, .tipped with one or two sensory filaments, 

 and often in the male surrounded at the base by a fascicle of them, 

 accessory or medial flagellum smaller than the principal, sometimes almost 

 imperceptible. Second antennae in female from one- to five-jointed, never 

 elongate ; in the adult male sometimes exceeding the length of the body by 

 the gradually elongated, many-jointed flagellum, the last two joints of the 

 peduncle often fringed with brush of sensory filaments, the whole apparatus 

 resembling similar structures among the Amphipoda and Phyllopoda, sheltered 

 when out of use at the sides of the body; the flagella in Lamprops are of 

 moderate length, prehensile, used for clasping the female. Upper lip simple, 

 often faintly emarginate. Lower lip bilobed. Mandible without palp, 

 with dentate cutting edge, accessory plate at least on one member of the 

 pair, a spine-row of spines varying from two to a score, molar stout or 

 rarely slender, base of the trunk usually narrowing to the rear, sometimes 

 broad. First maxillae as a rule with medial plate narrower than the 

 lateral, surrounded by few spines, lateral plate with about ten, the so-called 

 palp turned straight back or rarely absent, when present carrying distally 

 two filaments or a single filament, probably employed in cleansing the epipod 

 of the first maxillipeds and its branchial leaflets. Second maxillae generally 

 divided into two or tliree spiniferous plates, occasionally undivided. First 



