298 PKOCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



ACANTHOIDEA. 



* Solerochiton, Francisia, Dinoplax, Daivsonia, Beania, and Arthuria not examined. 



Acanthopleura Cpr. ex Guilding. , 



A. spinigera Sby. (Type.) Minor lateral large, shaft long, cusped, wings long, 

 narrow, linguiform; major lateral with a simi^le rounded cusp, shaft keeled, keel 

 with a cuspidate jirocess; inner nncini nodulose; major unciuus short, broad, thick. 

 Fig. 28. 



Lucia Gld. 



L. con/ossa Gld. (Type.) Minor lateral twisted, peculiar, outer wing broad, re- 

 ciu'ved at tij), inner wing small, strengthened by a branch from the shaft (Fig. 29a) ; 

 rhachidian- minute ; major lateral with a quadridcntate cusji, shaft with its inner 

 expansion terminating in a cuspidate process above ; inner two unciui ridged ; major 

 uncinus feather-shaped, vane on the inner edge (29 h). Fig. 29. 



Corephium Gray (not Brown). 



C. echinatum Sby. (Tyjie.) Minor lateral with the shaft expanded above, with a 

 cusp confluent with the ujiper edge of the small inner wing, outer wing small ; 

 major lateral with a rounded tridentate black-margined cusp bearing a spot on the 

 middle denticle, shaft keeled in front, keel i)roduced into a thin linguiform jirocess; 

 major uncinus asymmetrical, somewhat spoon-shaj)ed. Fig. 30. 



Nuttallina Cpr. 



K. scabra Eve. (Type.) Minor lateral normal, bi-alate; major lateral normal, 

 with plain shaft and tridentate cusft; major uncinus long, slender, with small ex- 

 pansion at the tip. Fig. 31. 



Phacellopleura Cpr. ex Guilding. 



P. porphyritica Eve. sp. unica. Minor lateral with an inner but no outer wing, 

 otherwise normal; major lateral normal, with plain shaft and tridentate cusp; inner 

 uncini nodulose ; major uncinus normal, 8]jatulate. Fig. 32. 



B.— lEEEGULAE CHITONS. 



SCUIZOIDEA. 



I have not been able to obtain the radula of any of the few species comprised in 

 the genera Loriea, Aulacochiton, iSchizochiton, Enoplocldton, and Onithochitan. 



Placiphoroidea. 

 Placiphora Cpr. ex Gray. 



F. CarmichaeUs Gray (:= C. setif/er King and Fremhli/i Brod.). Type. Ehachidian 

 tooth with its edges folded inward. Minor lateral with a large narrow inner wing, 

 small outer wing, and a median keel on the slender shaft; major lateral with a large 

 tridentate cusp, shaft slender, normal ; major unciuus with a small expansion at 

 the tip. Fig. 33. 



Euplacipliora, Frembhjia {== Streptochiton Cpr.), and Guildingia not examined. 



MOPALOIDEA. 



Mop all a Cpr. ex Gray. t^ 



M. ciliata Sby. (Type, = mnscosa Gld. -f- Hindsii Gray.) Minor lateral normal, 



bi-alate ; major lateral normal, tridentate with a plain shaft ; inner two uncini 



ridged; major uncinus rather short, normal. Fig. 35, 35 a. 



M. Wossnessensldi Midd. {Kennerlyi Cpr.). Similar to the last with a longer major 



uncinus. Fig. 34, 



Placiphorella Cpr. 



F.velata Cpr. (Type.) Ehachidian very largo; minor lateral unusually small, 

 both normal ; major lateral tridentate, normal. Fig. 3(5, 3G a. 



