1 8 JEFFERY : ON THE HAIRS OF MOLLUSCA, &C. 



I. In H. rufescens, Dr. Jeffreys states that ' the young are 

 really hispid up to four whorls.' I cannot endorse this state- 

 ment, in fact I take it to be an error. This is a very common 

 species here — far too common in my garden, and having 

 examined a great many during the summer, in no single instance 

 have I found a trace of hair or bristle. 



II. Of H. concinna he says ' epidermis sparsely covered 

 with short white hairs which are easily rubbed off' ; and further, 

 comparing it with H. hispida, ' more scattered and easily shed.' 



III. H. hispida. ' Epidermis closely covered with short 

 recurved white hairs, which are persistent and not easily rubbed 

 off.' 



IV. If. sericea. ' Epidermis closely covered with rather 

 long and very fine white downy hairs, which are persistent, and 

 when rubbed off leave their sockets very perceptible, giving the 

 surface in that case a finely granulated appearance.' 



V. H. revelata. ' Epidermis covered with short white 

 hairs, which are easily rubbed off.' 



VI. H. obvoluta. ' Epidermis very thick, closely covered 

 with stiff reddish-brown hairs.' 



My protest against including H. rufescens thus leaves us 

 with five species having hairs or bristles. I may say of H. 

 revelata I have not had an opportunity of examining specimens. 



In addition, however, to these, we may mention H. aculeata, 

 H. pulchella var. cosfata, amongst the land, and Planorbis 

 nautileus var. cristata, amongst the freshwater, as affording 

 somewhat analogous formations. 



IT. aculeata has a series of laminated plates, rising at 

 regular intervals, from the surface of the shell across the whorls, 

 and terminating in short thick bristles. 



H. pulchella var. costata and P. nautileus var. cristata have 

 similar plates, and in one of the specimens of the latter, in the 

 micro-slide, they may be seen approaching to something like a 

 spine. 



J.C, v., January, 1886. 



