52 CRUSTACEA OF ALABAMA. 



Fam. 6, Lynceid/e: 



A. Intestine not coiled. . . . . . . . Genus Eurycercus. 



B. Intestine coiled. 



a. Body somewhat elongate-oval or quadrangular. 

 * Head with a keel above. 



f Post-abdomen longer than half the length of elongate shell, becoming more narrow 

 toward the end. ...... Genus Camptocercus. 



tf Post-abdomen less than half the entire length of the elongate shell, of equal width. 



Genus Acroperus. 

 fff Post-abdomen about half as long as the short and very high shell. . Genus Alonopsis. 

 ** Head without a keel above. 

 \ Post-abdomen nearly round in outline, armed with very long stout spines, terminal claw 

 with one minute basal spine or none ; greatest hight of shell about equal to 'the poste- 

 rior margin. ■ . . . . . (see page 37) Genus Leydigia. 



ft Greatest hight of shell moderately exceeding that of posterior margin ; post-abdomen 

 ■ more or less triangular, armed with bristles; sheli marked with hexagonal meshes. 



(a) Head nearly horizontal, blunt; post-abdomen prominent in the anal region. 



Genus Graptoleberis. 



(b) Head depressed, acute ; post-abdomen excised near the anus. 



(page 38) Genus Crepidocercus 

 fff Post-abdomen more or less quadrangular, armed with one or two rows of small teeth 

 on either side behind; terminal claws with one or two basal spines; hight of poste- 

 rior shell margin usually less than the greatest hight of shell. 



(page 38) Genus Lynceus. 

 fttt- Greatest hight of shell little less than that of posterior shell margin ; post-abdomen 

 terete ; terminal claws very minute. .... Genus Phrixura. 



tfttt Greatest hight of shell more than double that of posterior margin. 



(a) Eye and first foot normal. .... Genus Chrydorus. 



(b) First foot with a claw which extends beyond the shell. . Genus Anchistropus. 



(c) Eye absent, only pigment fleck used for vision. . . Genus Monospilus. . 



IV. Order Copepoda. 



Fam. 1. Cyclopidte. Right and left antennae modified (geniculate.) in male, antennules not biramose, 



fifth feet alike in both sexes, two egg sacs. . . (P a g e 1 3) Genus Cyclops. 



Fam. 2. Calanid^e. Generally but one of male antennae geniculate, antennules bi-ramose, egg sac single, 



fifth feet of male generally modified. ..... (p a ge S-) 



Fam. 5. Harpacticid/e. Antennae of both sides geniculate in male, short antennules with a one-jointed 

 palp, fifth foot two-jointed, leaf-like, egg-sac single. . . . (p a ge r 8. ) 



III, V. Order Phyllopoda. 



Fam. 5ranchipodid;e. Body slender, thoracic segments distinct, eyes stalked, eggs carried in a sac be- 

 neath the abdomen. .... Streptelocephalus. Chirocephalus, Etc. 



Fam. Estherid^e. Body wholly or partly enclosed in a bivalved shell, eyes sessile. 

 Shell oval, sub-globose, without lines of growth, feet ten to twelve pairs. 



(page 38) Genus Limnetcs, Genus Estheria. 

 VII. Order Amphipoda. 



Fam. Orchestid«. Upper antennas shorter than lower, with no secondary flagellum, mandible not pal- 

 pate. ..... (P a g e 4°) Genus Orchestia. 



Fam. Gammarid^e. Upper antennae generally longer than lower, with a secondary flagellum, first and 

 second feet chelate. 



1. Telson (tail-fin) double, last pair of feet bi-ramose, three clusters of spines on the posterior 



margin of the fourth, fifth and sixth abdominal segments. . (page 40) Genus Gammarus. 



2. Telson single, last pair of feet with one ramus, clusters of spines absent. 



(page 40) Genus Crangonyx. 



