298 Prof. G. J. Allman on a new Genus of Gasteropods. 



cond is occasionally met with ; it is characterized by the spots 

 being of a pure white. 



Geomalacus is at once distinguished from Avion (to which how- 

 ever it appears to approach more nearly than to Limax) by the 

 position of the generative aperture, this orifice being placed in 

 Avion just below the entrance to the respiratory chamber^ while 

 in Geomalacus its position is similar to that in Limax, being just 

 behind the base of the smaller tentaculum of the right side. The 

 presence of a solid testaceous rudiment may be placed in con- 

 junction with the last as a character distinguishing it from Avion ; 

 though upon this, viewed isolatedly, much stress should not per- 

 haps be laid, as in the last-named genus the rudimental shell 

 would appear sometimes to assume a considerable degree of so- 

 lidity. From Limax the distinction is well-marked, being found 

 in the presence of a caudal muciferous follicle, and in the posi- 

 tion of the respiratory orifice anterior to the centre of the lateral 

 margin of the shield ; the total absence of a dorsal keel also is a 

 character by which Geomalacus resembles Avion rather than Li- 

 max. 



The habits of our mollusk are somewhat curious. It possesses 

 a singular power of elongating itself so as at times to assume the 

 appearance of a worm. By this means it can insinuate itself into 

 apertures which we could scarcely conceive it possible for it to 

 enter. This curious property indeed was very nearly the cause 

 of my losing the first, and at the time the only specimen I had 

 seen. I had placed the mollusk, as I supposed, securely in a 

 botanical collecting-box, when to my surprise I found shortly after 

 that it had transgressed the limits I had assigned it. The crea- 

 ture not liking its confinement had insinuated itself beneath the 

 lid, which not closing very perfectly had afibrded for its escape a 

 fissure of about a line in width. I was fortunately in time to 

 recapture my prisoner, and the knowledge which I had thus 

 gained of its habits suggested a stronger prison for the future. 



I have since been favoured by Mr. Andrews with numerous 

 very fine healthy specimens from the original locality, where the 

 mollusk is abundant, and beyond which it has not as yet been 

 detected. In an interesting letter which I have received from 

 this gentleman is a highly graphic description of Geomalacus 

 among its native rocks. From Mr. Andrews^s letter I cannot do 

 better than select the following extract as a conclusion to the 

 present notice : — 



" Lake, or Loc Carogh, lies to the south of Castlemain Bay, 

 in the county of Kerry, and stretches nearly north and south five 

 miles. The lake narrows at the centre, where huge cliffs (prin- 

 cipally of the old red sandstone group) rise precipitously from 

 the margin on either side to a great height. On the east side 



