PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 297 



Ischnoradsia Cpr. nou Shuttleworth. 



/. trifida Cpr. Minor lateral witla no outer wing, but a small process near the 

 apex of tlie shaft, which may represent it; inner wing normal; major lateral shaft 

 normal, cusp bidentate, with a spot behind the notch (Fig. 17«); uuciui rugose, 

 normal. Fig. 17. 



Lepidopleurus Cpr. nou Risso. 



L. MertcnsU JNIidd. Minor lateral with no outer wing; shaft cusped at apex, inner 

 wing normal; major lateral with a simple cusp, shaft normal, deeply channelled 

 behind. Fig. 18. Fig. IS a shows the appearance of the minor laterals and their 

 wings extending behind the rhachidian tooth as they do when in their natural posi- 

 tion. 



Lepidoradsia Cpr. {Lopliyrus pars Adams.) 



X. australis Sby. Minor lateral with a singular mushroom-like cusp with rudi- 

 ment of inner and no outer wing; major lateral bidentate, shaft keeled ^yith spatu- 

 late process; major uncinus short, broad, other uncini rather small. Fig. 19. 



Callistochiton Cpr. 



C. palmulatus Cpr. Minor lateral with a narrow inner wing parallel with and no 

 wider than the shaft, cusped at the top, outer wing absent or represented by a 

 minute cuspidate process; major lateral with a simple cusp, shaft with an anterior 

 keel bearing a sublauceolate process. Fig. 20. 



Callisloplax, Ceratophorus, and Newconihia not examined. 



Pallochiton Dall (= HempliUlia Cpr. MSS. nom. praeoc.). 



P. lanuginosus Cpr. Minor lateral normal, bi-alate; major lateral tridentate, shaft 

 normal. Fig. "21. 



LOPHYROIDEA. 



Chiton Cpr. Lin. not Adams. Type C. tuberculatus I>iu. (Lojihi/rus H. & A. Ad. not Poll). 



C. articulatm Sby. Minor lateral with no outer wing, shaft small, narrow, prone, 

 from which extends the greatly elongated cusped inner wing external to the rha- 

 chidian tooth ; major lateral with a simple rounded yellowish cusp with a black 

 margin marked by a peculiar spot ; shaft normal, with an inner lateral expansion pro- 

 duced into a linguiform process; major uncinus broad, long, spatulate; outer unci- 

 nus transversely elongated. Fig. 22. Fig. 22a, side view of rhachidian tooth. 



C. Sfokesli Brod. Minor lateral with expanded inner wing, shaft cuspidate, cusp 

 twisted and outer wing reduced to a portion of this cusp or absent; major lateral 

 with an elongated simple cusp, shaft thick, strong, keeled in front, keel bearing a 

 blade-sha|)e<l process attached to the keel at two points, with a small foramen between 

 them; major uncinus short, broad, somewhat plume-shaped. Fig. 24. Fig. 24a, 

 major uncinus, from lielow. 



C. Ciimingii Frembly. Minor lateral normal, with wings recurved above and on 

 each side; major lateral with simple elongate cusp, shaft with a strong keel bent 

 outward below and produced above into a strong spoon-shaped process ; two inner 

 uncini nodulose ; major uncinus with a slender and rather straight shaft. Fig. 25. 



C. assirnUis Rve. Minor lateral; shaft with small or nearly abortive wings, base 

 long and recurved ; major lateral with a simple rounded cusp, a keel on the shaft 

 bearing a spattilate ]5rocess; major uncinus feather-shaped, the vane on the inner 

 side. Fig. 2G. 



Tonicia Gray. 



T. elcgans Frembly. (Type.) Minor lateral leaf-shaped, normal, apex curved for- 

 ward ; major lateral with an orange, black-edged, rounded, simule cusp with a spot 

 on the margin, shaft normal ; major uncinus very much twisted and deciu'ved, 

 spatulate. Fig. 27. 



Eadsia, Fanmjla, Eiidoxocliiton, and Crusptdochlion not examined. 



