On the Generic Affinities of the New-England Chitons. 119 



about one half and one third as lono; as the precedino-. Abdomen 

 ending ni a short conical process. Copulative organs^ of the 

 male of complex structure, the basal portion on each side con- 

 sisting of a subrhomboidal acuminate lamina, the apical portion 

 of an irregularly shaped plate produced laterally into an aliform 

 process, and on the distal margin into a short strong hook. 

 Female probably viviparous. 



EXPLANATION OF THE PLATES. 



Plate IV. 



Fig. 1. Cijthcrura fulva, male, seeu from right side. 1 



Fig. 2. The same, male, seen from above. ) 



Fig. 3. The same, male, seen from end. )- X 84. 



Fig. 4. The same, female, seen fi-om right side. | 



Fig. 5. The same, female, seen from below. j 



Fig. 6. CytJierura Sarsii, seen from right side. 1 q. 



Fig. 7. The same, seen from above. / * 



Fig. 8. Xestoleheris labiata, female, seen from left side. ^ 



Fig. 9. The same, female, seen from above. 



Fig. 10. The same, female, seen from below. 



Fig. 11. The same, female, seen from end. v -.. 



Fig. 12. The same, male, seen from left side. ;'X-j . 



Fig. 13. The same, male, seen from below. 



Fig. 14. The same, left valve, seen from inside. 



Fig. 15. The same, right valve, seen from inside. J 



Plate V. 



Fig. 1. Cgtherideis suhulata, var., seen fi'om right side. ) 



Fig. 2. The same, var., seen from above. j- X'"iO. 



Fig. 3. The same, var., seen fi'om below. ) 



Fig. 4. The same, anterior margin of shell. X 84. 



Fig. 6. The same, shell-structme. x 100. 



Fig. 0. FaracJoxostoma cuneatum, seen from right side. "I .-/) 



Fig. 7. The same, seen fi'om below. J "^ ' 



Fig. 8. DancineUa Stevensoni, mandible and palp : a, mandible ;"" 



b, palp ; c, branchial plate. 

 Fig. 9. The same, first jaw : a, incisive lobes ; i, branchial plate. ^x220. 

 Fig. 10. The same, second jaw : a, maxilla j h, pedifoim palp; 



c, branchial plate. 



XVI. — On the Generic Affinities of the Nevo-Encjland Chitons. 

 By Philip P. Carpenter, of Montreal*. 



It has been common, with conchologists even of the " ad- 

 vanced " school, to call every mollusk with eight valves a 

 Chiton^ except the vermiform species, which Lamarck sepa- 



* Communicated by the Author, having been read at the Meeting of 

 the American Association for the Advancement of Science, held at Port- 

 laud, August 1873. 



