150 MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES. 



EXPLANATION OF THE PLATES. 



Plate I. 



Fig. 1. Cauloxenus stygius Cope. — la, 16, lc, the same in different positions ; a, b, antennae ; c, mandible (?); x, point of 



attachment of arms to its host. Highly magnified. 

 Fig. 2. Canthocamptns cavernarum Pack. — 2a, head, showing the antennules and antenna ; st., stomach ; 26, the second 



antennae, more magnified ; 2c, end of the body, dorsal view ; 2d, the same, enlarged. Author del. 



Plate II. 



Fig. 1. Asellus communis, from Indiana. — Antennule (first antenna) ; la, end of the same, showing the three olfactory 

 rods; 16, lc, mandibles, with palpus (palp.) ; Id, le, first maxilla (?) (compare PI. Ill, fig. 2i); 1/, first maxilla 

 of authors; lg, second maxilla ; lft, the same, incompletely drawn ; li, maxillipede; st., stipes ; 1. 1., lateral 

 lobe; palp., palpus; lab., lobe of the labium; x, delicate membranous processes connecting the opposing 

 edges of the labial lobes; lj, first pair of male genital armature; lfc, second or last pair of male genital 

 armature ; 1 1, penis. 



Fig. 2. Asellus intermedins Forbes (drawn from specimens labeled by him). — Antennule; 2a, second joint of the 

 same, showing two auditory setae ; 26, end of the same, showing three olfactory rods, the terminal joint 

 ending in three setae (one broken off) ; 2c, auditory seta? ; 2e, an olfactory rod ; 2/, one of the last uropoda, 

 the setae unusually long and numerous in this species. 



Fig. 3. Asellus brevicauda Forbes (drawn from specimens labeled by him). — Antennule; 3a, second joint of the same, 

 with four auditory setae ; 36, end of the same, with three olfactory rods ; 3c, a leg of the first pair, male ; 

 3d, a uropod of the last pair (its mate was much shorter). Author del. 



Plate III. 



Fig. 1. Ccecidotwa stygia Pack. Drawn by J. S. Kingsley from a specimen exactly like one from Mammoth Cave; 

 the details drawn from a Mammoth Cave specimen, la, larger antenna ; 16, cercopod, 2 ; lc, cercopod, J 1 ; 

 Id!, one of the terminal setae, much larger than the others and bulbous at the end. 



Fig. 2a. C. stygia. — Antennule of short form from the Labyrinth, Mammoth Cave ; 26, end of 2a, with the three olfac- 

 tory rods; 2c, 9 antennule ; ol., olfactory rods; 2d, the same, enlarged, showing the four terminal joints filled 

 with nerve cells (n. cells), and the auditory bristle (and. s) ; 2e, first maxilla (of authors) ; 2/, the same 

 enlarged, the outer lobe bearing ten or eleven 6imple setae, the inner lobe five spinulated setae ; 2g, second 

 maxilla (of authors); 2ft, end of same, enlarged, each of the two outer lobes bearing on the inner edge six 

 or seven curious comb like setae (not very well represented in the plate), the other setae transversely stri- 

 ated; 2i, the second pair of appendages behind the mandibles (first maxilla?). 



Fig. 3, 3a. C. stygia Forbes, from a well in Illinois. — Second joint of antennule, with three auditory bristles ; 3a', three 

 basal joints of antennule from a Mammoth Cave individual, with an auditory bristle on the basal and two 

 on the second joint. 



Fig. 4. C. stygia, from Annville, Pennsylvania. — Antennule of seventeen joints — 4a, end of the same, with six olfac- 

 tory rods, three of which are on the sixth joint from the end. 



Fig. 5. C. stygia, from Long Cave. — Antennule ; 5a, antennule of another individual from the same cave, with but • 

 eight joints; 56,5c, antennae of the same; bd, a leg of the first pair, 2 adult, with eggs. 



Fig. 6. C. stygia, collected in daylight, 50 feet in from entrance of Walnut Hill Spring Cave, attennule; 6a, terminal 

 joints of the same. 



Fig. 7. C. stygia, from Bradford Cave. — Antennule of ten to eleven joints. 



Fig. 8. C. stygia, from Carter (X) Cave — 8a, terminal joints of the antennule, with five olfactory rods. 



Fig. 9. C. nickajackensis. — Antennule; 9a, terminal joints. 



All the figures except one drawn by the author. 



Plate IV. 



Fig. 1. Ccecidotcea stygia Pack., from Mammoth Cave. — 2 mandibles (inside) ; la, right mandible (on the outside) ; m, 



muscles; palp., palpus; 16, maxillipede ; si., stipes; l.l., lateral lobe; palp., palpus ; lab., labium; lc, labium 



and palpus of 16 ; Id, one of the first pair of feet, $ ; le, the same, 2 ; 1/, seventh leg, $ ; lg, the same, 2 ; 1ft. 



first abdominal legs, $ ; li, one of the second pair, $ ; lj, under side of abdomen, $ ; Ik, the coupling organs, 



, magnified ; x, clasper's ; 1Z, underside of abdomen, 2 ; lm, the same with the outer appendages removed. 



