NATURAL SCIENCES OF PHILADELPHIA. 141 



The second grand division contains those genera having a jaw. 

 In this division also we find some genera with aculeate, and some 

 with quadrate, marginal teeth. 



Of the former are: Limax, 1 Ibycus* Parmacella? Tennentia* 

 MariellaP Parmarion, 6 Dendroliniaxf Phosphorax ? 8 UrocyclusP 

 [I know nothing of the position of Othelosoma, Aspidorus, and 

 other problematical genera.] Vitrina, 10 VitrinoideaJ 1 Vitrinopsis, 12 

 Nanina and all the genera now recognized in its disentegration, 

 Stenopus, u Vitrinoconus, 15 MacrocyclisJ 6 Zonites." 



The following genera have quadrate marginal teeth. They may 

 be readily grouped by the character of their jaw, which is either 

 in one single piece, in one single piece with an accessory upper 

 quadrate piece, or in numerous pieces. 



Those whose jaw is in one single piece may again be subdivided 

 into several groups based on the absence, presence, and peculiari- 

 ties of the ribs on their jaw. This division, however, is unsatis- 

 factory, as these characters are not always well marked. 



(a) Jaw without ribs : Philomycus ParmellaV 9 Oopelta Ana- 

 derus, 11 Sagda, 2 ' 2 Patula, 23 Polymita, 24 Hemitrochus, 25 HelicodiscusJ 26 



1 See this paper. 



2 Heynemann, Malak. Blatt. X. 142, pi. I., fig. 3. 



5 Semper, Phil. Archipell. 90. 



* Semper, 1. c. 1, pi. VI., fig. 17. 5 lb. 12. 



6 lb. 9, pi. VI., fig. 10. 



7 Heyuemann, Malak. Blatt. XV., pi. I., fig. 1. 



8 Jaw arid tongue not known. 



9 Heynemann, Malak. Blatt. 1866, 70, pi. XL, as Parmarion flavescens. 



10 See this paper. 



11 Semper, 1. c. 85, pi. IX., fig. 33. 



12 Ibid. 86, pi. XL, fig. 26. ' 3 Ibid. 

 Bland, Ann. Lye. X. H. of N. Y., VIII. , 158, fig. 



15 Semper, 1 c, 91, pi. XL, fig. 27. 



18 See this paper. !r See this paper. 



18 See this paper. 



19 Jaw and lingual dentition unknown. 



20 Heynemann, Malk. Blatt. XIV., pi. I., 2. 



21 Heynemann, Malk. Blatt. X., 138, pi. I., fig. 1. 



22 Bland and Binney, Am. Journ. Conch. VI., 177. 



23 See this paper. 



2 * Bland and Binney, Ann. Lye. N. H. of N. Y., X.,341, pi. XVI., fig. 1. 

 25 See this paper. *> See this paper. 



