692 PROCEEDINGS OF THE NATIONAL MUSEUM. vouxx. 



The brancliial formula for P. agassizii is as follows : 



Akthrobeanchi^. 



Somite. Podobranchi^. . Pleurobranchi^. 



Anterior. Posterior. 



VII. . . . 0(ep) ..0....0....0 = 0(ep) 

 VIII. ...1....1....0....0 =2 

 IX. ... 1 .... 1 .... 1 .... =3 



XI. ... 1 .... 1 .... 1 .... 1 =4 



XII. ...1....1....1....1 =4 



XIII. ... 1 .... 1 .... r .... 1 = 3+r 



XIV. ... .... .... 



6+op +6 + 4+;' + 4 = 20+r+ep 



The epipod of the first maxilliped is destitute of branchial filaments, 

 a condition rarely found among the Parastacince. The stems of the 

 podobranchiffi are alate. The posterior arthrobranchia of the thir- 

 teenth somite is a simjile, slender filament. Coxopoditic setae long, 

 hooked at the free end. 



Habitat. — Talcahuano, Chile, No. 3400, Coll. Mus. Comp. Zool., (Hass- 

 ler Exped., April, 1872). Nine males, eight females (two ovig.). 



The egg measures 3.5 by 2.5 mm. 



In nine out of fourteen specimens the larger claw is on the left side. 



Judging from the form of the body, this is probably not a burro wing- 

 species. 



Museum of Comparative Zoology^ 



Cambridge^ Massachusetts, August 1, 1896. 



EXPLANATION OF PLATES. 



[XoTE. — All of the figures were drawn by James H. Einertoii. Owing to errors in the photographic 

 reduction of the original drawings, it is impossible to give the exact scale for many of the figures 

 in these plates.] 



Plate LXII. 



Fig. 1. Cambarus achcrontis Liinnberg. Female. Gum Cave, Citrus County, Florida. 

 Reduced. (U.S.N. M.) 



2. The same, lateral view of the head. 



3. Camharua acherontis Liinuberg. First abdominal appendage of a young 



male, Form II, from the outside. 



4. The same, from the inside. 



5. Cambarus acherontis Liiunberg. Annulus ventralis of adult female. 



6. Cambarus longidigitiis Faxon. Male, Form II. White River, Arkansas. 



Reduced. (No. 4364, Mus. Comp. Zool. ) 



7. The same, first abdominal appendage from the outside. 



8. The same, first abdominal api)endage from the iuside. 



9. Cambarus longidigitus Faxon. Annulus ventralis of female. 



Plate LXIII. 



Fig. 1. Cambarus carinatus Faxon. Male, Form I. Guadalajara, Mexico. Xf. (No. 

 17699, U.S.N.M.) 



2. The same, first abdominal appendage from the outside, 



3. The same, first abdominal appendage from the inside. 



