160 Notes on certain Terrestrial Mollusca. 



In a paper " On the Structure of the Axis of the Shell of 

 Cylindrella" {Annals vi. 150, 1855), I pointed out the peculiar 

 nature of the axis in several species, and observations have 

 since been made on its singular character in other and espe- 

 cially in Cuban species. 



In C. turris Pfr. of Mexico, the axis is a highly polished tube, 

 the exterior of which is distantly but strongly ribbed, having a 

 diameter, in the fourth whorl from the last, of 4-5 mill., so that 

 a young shell must have a wide open umbilicus. This tube 

 has a groove or sinus within each whorl, immediately above 

 the septum. The tube gradually increases in size from the 

 apex, but is smaller towards the base ; in the penultimate 

 whorl it is 3 mill, in diameter ; in the last it rapidly diminishes, 

 and terminates in a point, the umbilicus being imperforate. A 

 similar structure prevails in 0. clava Pfr., also from Mexico. 



The internal structure of C. Goldfussi Menke of Texas, be- 

 longing to the subgenus Holospira, differs essentially from that 

 of any West Indian form which has come under my notice, and 

 I have examined very many. 



In the penultimate whorl of C. Goldfussi there are four 

 lamellae : one strongly developed, situated on the under side of 

 the upper septum, and in length about equal to one-half of the 

 circumference of the whorl ; another on the upper surface of 

 the lower septum, immediately beneath and opposite to the 

 above-mentioned lamella, and of about equal length, but not so 

 much developed ; a third lamella on the middle, of the lower 

 half of, and revolving on the axis ; the fourth on the inner side 

 of the outer wall of the shell (opposite the axial lamella), and 

 visible from the exterior. I am not aware of the occurrence of 

 lamina on the outer wall or septa of the whorls in any other 

 species, but have not had an opportunity of examining several 

 which are allied to C. Goldfussi. 



The animal of Cylindrella has no buccal plate — at least it has 

 not, so far as I am informed, been detected. 



The lingual dentition varies considerably in different species. 



