162 On the Systematic Arrangement of 



The genus Holospira, with the two species H. R'demeri 

 and H, Goldfussi, must be phiced, together with Cylindrtlla 

 and Macroceramus, as ah-eady mentioned with regard to 

 those genera, in the family Helicidon. 



Macroceramus. — In this genus the jaw and lingual mem- 

 brane are as in Cylindrella, and our description (page 219) 

 must be cancelled. In M. Gossei, however, the teeth are 

 the same as in Helix, with bluntly pointed denticles, one 

 long and the other short, as shown in our above referred to 

 figure. 



Helicid^ (p. 25). — More recent investigations have 

 satisfied us that the presence of a mucus pore is not in itself 

 a character to warrant the separation of the Arionidce as a 

 family. It has been shown that the pore exists, with various 

 moditications, in many species of Geophila where it was not 

 before suspected, for instance in Helix pylaica, Glandina 

 liyulata {Petenia, Crosse, Journ. Conch. 1869, p. 35), Glan- 

 dina monilifera (Morelet, ibid., 1852). Unless, then, we 

 are prepared to consider these species as belonging to a 

 family distinct from Helix and Glandina respectively, we 

 cannot separate the Arionidoi from the Helicidce on account 

 of the presence alone of the mucus pore. 



The description of the foot of Helicidoe (p. 25) should be 

 modified by the addition of the following words : "or with a 

 distinct locomotive disk," and " or with a caudal mucus pore." 



To the description of the jaw must be added the words 

 " or with one upper, accessory plate. Jaw sometimes want- 

 ing." The last reference is necessary to embrace such cases 

 as Helix incequalis, a species, however, which may be proved 

 to belong to another family. 



As a basis for grouping the large number of genera of 

 Helicidoi into subfamilies, we retain the characters of the jaw 

 and teeth, but with some modifications, as shown in the 

 following synopsis. The subfamily JPupinm is eutirely sup- 

 pressed, as it has been shown that no reliance can be placed 

 on the median beak-like prominence to the cutting edge of 



