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MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 151 



Fig. 2. C. atygia, from Carter Cave. — One of first pair of legs, 2 . 



Fig. 3. Asellits communis Say. — Antennule, $ , showing the three auditory bristles; 3a, end of 3, with olfactory rods 

 much shorter than in C. stygia; 3b, antennule 2, with five auditory bristles ; 3c, the same of another indi- 

 vidual; 3d, antennule ; 3e, antenna, <J , from Illinois; 3/, mandible; 3g, one of the first pair of legs, $; 3k> 

 left cercopod, $ , from Irvington, Indiana. Author del. 



Fig. 4. Asellus, sp. indet., from Gill's Branch, near Lancaster, Garrard County, Kentucky. Kiugsley del. 



Fig. 5. Undetermined ; locality unknown. Kingsley del. 



Plate V. 



Fig. 1. Crangonyx vitreus (Cope). — 2 , 5.2 mm long, enlarged 20 diameters. 



Fig. 2. One of the first pair of legs seen from the outside, enlarged 48 diameters. 



Fig. 3. One of the second pair of legs, x 48. 



Fig. 4. End of the abdomen, side view, X48. — a, telson ; 6, posterior caudal stylet ; c, second caudal stylet ; d, first 



caudal stylet. 

 Fig. 5. Crangonyx packardii Smith (details all magnified 48 diameters; 5 to 8, 2, 5.5 mm long; 9 to 11, J, about 7.5 mm 



long). — Lateral view of the head. 

 Fig. 6. End of one of the first pair of legs, outside. 

 Fig. 7. The same of the second pair. 

 Fig. 8. End of the abdomen, lateral view. 

 Fig. 9. One of the first pair of legs, outside. 

 Fig. 10. One of the second pair of legs, outside. 

 Fig. 11. Autenn.ula and antenna, side view. 



Fig. 12. Crangonyx antennatus Pack. — Terminal joints of the antennnle, showing the olfactory rods. 

 Fig. 13. The entire- antennnle. 13a, basal joint with four auditory set® ; 136, fourth joint of the same with its ramus. 

 Fig. 14. Antenna, with four auditory seta?. 

 Fig. 15. Crangonyx mucronatua Forbes, Illinois. — Antenna, end enlarged; 15a, the same more highly magnified ; 156> 



fourth joint still more magnified. (The setulse of the auditory setse are fewer than in Cascidotaa.) 

 Fig. 16. Crangonyx vitreus Cope (?) .—Basal joint of antennnle. (Compare with Fig. 13a.) 

 Figs. 1 to 11 drawn by Prof. S. I. Smith. Figs. 12 to 16 drawn by the author. 



Plate VI. 



Fig. 1. Paeudotremia cavernarum (Cope), from Wyandotte Cave, enlarged. — la, head; 16, the same, front view; Id, 

 eyes. (Emerton del.) le, eyes of a Wyandotte Cave specimen; If, antenna much enlarged ; 1/', terminal 

 joint highly magnified, filled with nerve cells, with numerous tactile set;e, and two tactile or olfactory (?) rods 

 at the end; \g, under lip or dentomala (compare PI. VIII, fig. If, and explanation) ; l/i, labrum, with the 

 three central teeth; li, external malella {mat. c), internal malella (mal. i), and labiella (Za&); Ik, man- 

 dible of one side; lm, the same on the other side ; In, six bundles of seta? on the free edge of lm; lo, eighth 

 pair of legs ; lo', one of the legs enlarged ; lp, a leg of the first pair, next to tbe head ; lq, a leg of the last 

 pair; 1?-, a pair of normal legs ; Is, male genital armature ; It, the same, different view ; 1», end of the body ; 

 Iv, a segment (dorsal view). Author del. 



Fig. 2. P. cavernarum var. carterensia Pack., enlarged. — 2a, head enlarged; 26, side view of another specimen, x6; 

 2c, dorsal view of a segment. Emerton del. 



Plate VII. 



Fig. 1. Zygonopua whitei Eyder. — Anterior part of the body without the legs; la, front view of the head; 16, male 

 antenna; lc, three segments, enlarged to show the mode of origin of the lateral seta; ; Id, le, origin of the 

 same with the transversely striated area below the flattened boss from which the set;e arise ; If, one of the 

 sixth pair of legs of the male, forming claspers; Ig, a leg of the seventh pair of the male; l/i, a rudimentary 

 leg of the eighth pair (without a claw) ; lfc, rudimentary male genital ar .nature, with a rudimentary claw- 

 less leg on one side : 1/, lm', lamina interior ; lm', a bristly seta, very minute (compare PI. VIIT, fig. li', ml) ; 

 In, male genital armature, lamina exterior (I.e.) ; lo, the latter enlarged (1^, lq, antenna and labrum, etc., 

 of Zygonopua (?) or Trichopetalum). 



Fig. 2. Trichopetalum 1 una turn Harger.— Head and first three segments; 2a, nearly front view of head; 26, antenna; 

 2c, two terminal joints still more magnified ; 2d, leg; 2e, a rudimentary leg; 2/, two segments, showing the 

 swollen area bearing three seta}. 



Fig. 3. Antenme of Paeudotremia cavernarum.— a, one from Little Wyandotte Cave ; 6, from Bradford, and c, from 

 Carter (Bat) caves; 3d, 3c, '.!/, not accurately copied by the artist from the author's camera drawings. 



FlG ! . Eyes &f Paeudotremia cavernarum from different individuals from Bradford Cave. 



Fig. 5. Scoter pes copei Pack.— A pair of legs. 



All the figures drawn by the author with the camera lucida. 



