Nkwton, on the Helices and Limaces. 29 



tance from its base, and to tlie parietes of the body around 

 its base. 



In consequence of the position of the great retractor 

 muscles in the Limaces, the intestine curls round them 

 shortly before entering the pulmonary chamber. In L. 

 mawimus, after making this curl round the muscles, the in- 

 testine passes along the dorsal surface of the visceral cavity 

 nearly to the tail ; it then bends sharply back and returns 

 upon itself, terminating in the usual manner ; there is a con- 

 striction at the last bend (fig. 5 y) . L. flavus has, in place of 

 this backward turn of the intestine, a large csecum, which 

 occupies a similar position (fig. 6 a'). Mr. Binney notices a 

 small csecum upon the rectum of L. agrestis. 



It appears to be a general arrangement in both the Helices 

 and Limaces that the retractor muscle of the right superior 

 tentacle should pass between the male and the female re- 

 productive organs. The position of the generative orifice 

 being further back in Arion would lead us to expect a change 

 in this arrangement, and we accordingly find in A. ater (and 

 it may be the same in other species of this genus) that it 

 passes altogether below these organs. L. Soiverbii is anotlier 

 exception to this general arrangement, although the opening 

 of the reproductive organs occupies the normal position. 



Having, by the great kindness of Professor Busk, had access 

 to notes made by him some years back upon this subject, 

 and which chiefly relate to the microscopic contents and 

 structure of the various portions of the reproductive system, 

 I am enabled to append the general results of his observa- 

 tions. 



The ovotestis, like most of the other organs, was found to 

 vary much, as regards its contents, in different individuals. 

 Sometimes it contained abundance of spermatozoa, both 

 coiled and uncoiled (fig. a), with granular cells (fig. b) and 

 activer moleaules, the molecules being occasionally con- 

 tained in cells, in which case they were most active. At 

 other times there were but few spermatozoa, with nucleated 

 cells, some being in groups (fig. c), and active molecules. 

 Again, in other cases there were found transparent cells 

 with granular nuclei, which burst readily in water; small 

 granular cells, with highly refracting nuclei; and small 

 transparent cells, apparently having no nucleus. In the ovo- 

 testis of a H. aspersa, taken whilst laying its eggs, there were 

 transparent globules of various sizes (fig. d), which were 

 rendered opaque by acetic acid, and with these a few nucle- 

 ated cells. 



The epididymis, in abnost every case, contained sperma- 



