140 PKOCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



ON THE ANATOMY OF ABEOUBIS SUBCAEINATUS, Montagu. 



By M. r. Woodward, 

 Demonstrator of Zoology, Royal College of Science, London. 



Eead IZth May, 1898. 



PLATE VIII. 



The investigation of the anatomy of this minute Gastropod was 

 undertaken at the suggestion of my friend Mr. E. E,. Sykcs, who 

 drew my attention to the uncertainty prevailing as to the true 

 systematic position of this mollusc, and kindly offered to obtain for 

 me some living examples from Guernsey, his great experience in 

 shore-collecting in that island enabling him to procure living 

 specimens almost with certainty. Mr. Sykes also provided me with 

 references to the principal works dealing with the anatomy and 

 affinities of this form, and he has further kindly drawn up the 

 following short account of its habitat. 



Live examples of Adeorhis are only to be found under stones of 

 large size, that are deeply embedded in the sandy mud close to low- 

 water mark. The most likely stones are so large and firmly planted 

 that one person unaided can barely lift them. The sand or mud 

 beneath must not be too foetid. Generally it is stained yellow, and so 

 too is tbat portion of the stone on which the Adeorlis is found ; in 

 fact, it is quite useless to look for live Adeorhis if the sandy mud 

 under the stone be altogether black, as it so frequently is. The shells 

 themselves are frequently stained yellow in places, and sometimes 

 are partly blackened. 



With Adeorhis occurs a very interesting fauna, consisting of 

 Lepidopleurus scahridiis, Jeff., Rissoia cancellata, Da C, R. lactea, 

 Mich., R. striatula, Mont., and, occasionally, other species of Rissoia. 

 Adeorhis is found in Jersey, Guernsey, and Herm. 



Unfortunately the weather of last summer was not propitious for 

 shore- collecting, and Mr. Sykes was only able to secure three living 

 specimens, wbich he handed over to me. My own attempts to obtain 

 Adeorhis in Sark were unsuccessful, the prevalence of strong westerly 

 winds making collecting at low- water mark almost impracticable. 



The three specimens which Mr. Sykes obtained, I was able to 

 keep alive for some days, during which time I made a careful study 

 of the external form of this little animal ; they were afterwards 

 preserved in alcohol, and two of them, after their shells had been 

 decalcified, were stained, embedded, and cut into serial sections with 

 a microtome ; while from the thiixl the radula was extracted. The 

 small size of these animals rendered dissection almost an impossibility, 

 so that it was deemed advisable to cut them into serial sections, in 

 spite of the labour required in the reconstruction of the anatomy 

 from the same. 



Adeorhis is very easily kept alive for some days in a glass tube, 

 provided that the water is changed every day or two. Here the 



