182 Transactions. 



Iron Pyrites is a very widely distributed mineral, and may be 

 found almost anywhere ; in the above lists, only localities are 

 given where really good specimens can be got. 



II. On the Anatomy of Arion hortoisis. By Mr John Rutherford 

 (late Secretary). 



It was through some remarks and suggestions of our Presi- 

 dent, that I was induced to take up the study of the structure of 

 this slug. The whole of the work, including the diagrams, is 

 original. 



Arion hortensis belongs to the family, Limacidse — Genus 

 Arion. This slug is very common ; may be found almost every- 

 where in company witli Liinax agrestis and other representatives 

 of the slug family, and, after a little eye-training, its special charac- 

 teristics become quite familiar. It has many varieties of colour, 

 its fixed and marked distinctive features being its lateral longi- 

 tudinal bands, running from the caudal gland along each side of 

 the body, crossing the mantle on the upper margin of the respiratory 

 orifice, and terminating at its anterior edge. It has sometimes a 

 narrow border of grey, rufous, or orange colour. The foot is often 

 tinged with yellow, the dorsal part a darkish grey. Length is 

 from If to 2 inches. It has four anterior processes, two superior, 

 and two inferior. The latter pair I believe to be feelers, in which 

 is located the sense of smell. The superior pair, which are slightly 

 knobed, are the eyes, the eye proper occupying the knob or apex 

 of the process. It has cornea, crystalline lens, choroid, and optic 

 nerve ; is very short-sighted, not having any distinct vision beyond 

 a quarter of an inch. The advantage of these pediculated eyes 

 to the animal must be great, as it can turn in any direction (volun- 

 tarily) one eye, or both. The eyes, with their columella, can be 

 drawn into the body by the retractor muscle, which is attached in 

 such a way that the eyeball is first turned round, then the colu- 

 mella is drawn in, exactly as the finger of a glove would be if a 

 string was fastened to its inside point and drawn into the palm. 

 To extract the crystalline lens, snip off the eye with a pair of 

 scissors, put under pressure under the microscope, when the lens 

 will be forced out of its place and will float in the surrounding 

 fluid. 



The appendage known as the mantle is a fold or overlapping 

 of the integument, in the right border of which is the respiratory 

 orifice. Under the fold, on the same side, is the vent and common 



