HARD WICKE ' S S CIENCE- G OSS IF. 



277 



exquisite side illumination of tlie objects viewed. In 

 this manner the dots or striae of diatom, &c. are 

 lirought out with remarkable distinctness. Mr. 

 Ilinton has conferred a favour on microscopists by 

 bringing out this cheap and effective auxiliary. 



ZOOLOGY. 



The Mollusca of Derry.— During the last six 

 months I Jiave been busily hunting for shells in the 

 district immediately round the mouth of the river 

 Baun, CO. Derry, and I think some of your corre- 

 spondents might be interesteil to know that there is 

 an excellent field for conchological exploration in 

 that locality. Of course fresh-water shells were in 

 the mud during most of the time, and the only 

 capture worth mentioning was L. pahistns, var. 

 tiiicta, which swarms on the river banks. Witli 

 land shells I was much more fortunate, securing 

 in all forty-four different species. I will mention 

 a few of the most noteworthy. All the Zonites 

 except Z. glaber and Z. excavatus figure in my list, 

 Z. cella7-iiis being very fine and variable. The type 

 of Z. alUarius I rarely found, but the variety is ver>' 

 common. The varieties oi Z. purus and Z. radiaiiis 

 I also found — the former commonly. H. coiiciiiiia, 

 //. hispida, H. rotundala, and //. acitlcata, all 

 afforded me one or more albino varieties. C. lubrica 

 is extremely variable in size and is frequently clouded, 

 I secured one specimen of the var. hyaliita. The 

 sandhills at the Baun mouth are rich in some of the 

 less common Vertigoes; V. pygiihca (com.); /'. 

 subslriata (m.c.) ; V.piisilla (m.r.) ; T. angnstior (c.) ; 

 all of which I found among the drift in the hollows 

 dead ; but as the season advances, live specimens 

 ought to be met with. I secured one live specimen 

 of /'. alpcsiris under a stone by the river, and as this 

 last was new to Ireland, I was doubtful of its identity 

 and sent it to Dr. Jeffreys who confirmed my opinion. 

 V. edentiila and its var. colniuella are common in the 

 district among leaves and in woods, but not among 

 the sand hills. One captive has particularly pleased 

 me, viz. a specimen of V. pelliicida, with two 

 beautiful milk-white bands running spirally from 

 apex to mouth. B. acidus and its varieties are 

 particularly large and handsome on the Portrush 

 sandhills. On these sandhills I have observed a 

 phenomenon which has puzzled me much, and 

 should be glad of an explanation. At the mouths of 

 the countless rabbit burrows there were, during this 

 autumn, piles of H. ncnioralis, with //. aspersa and 

 a few PP. cricetonim, empty and apparently gnawed — 

 not broken in the way that we find them on " thrush 

 stones." The only conclusion I can come to is that 

 the rabbits eat them, but I do not know that anyone 

 has oliserved this habit in rabbits — though rats are 

 said to eat snails. I will not encroach further on 



your space, l)ut should any one, interested in the 

 subject, wish for more minute details of the district, 

 with a view to further search, I should be glad to 

 furnish him with them. A great deal might be said 

 about the marine shells on this part of the coast. — 

 Lionel E. Adams. 



The Mollusca of Maidenhead.— As far as I 

 am aware, there is no published list of the land 

 shells of the Maidenhead district, and so the following 

 list of shells, although by no means complete, as they 

 were all taken on the evening of July 6th, may be of 

 some use to collectors subsequently visiting the 

 locality. They were all taken in the immediate 

 neighbourhood of Castle Hill, and are as follows :— 

 Anon atcr: I found three full-grown specimens, 

 two were entirely black, and the third belonged to 

 the var. rufa, being of a dark brown colour. I 

 found one of the black specimens in the act of 

 devouring a dead worm, thus proving conclusively 

 that this species is not altogether a vegetarian. 

 Arion hortensis, one specimen ; Limax agrcstis, 

 Zonites cellariiis, Z. niiidiihts, Z. aUiariiis, var. viri- 

 dula — in shape this specimen is not unlike a young 

 Cellarius, but from the dark colour of the animal, the 

 strong garlic odour, and the fact that no greenish- 

 white form of cellarius has hitherto been recorded, I 

 think I am right in referring it to viridula ; I only 

 got one specimen. PPelix aspersa, H. rufcscens, H. 

 Cantiana, PP. Iiortensis, and vars. arcnicola, hitea, and 

 albina, arcnicola being very common. PI. nenioralis, 

 amongst ivy, //. lapicida, PP. hispida, Cochlicopa 

 lubrica, Clausilia laiiiinaia, and C. rugosa. On the 

 same day I found PP. hortensis and \ar. incarnata, and 

 IP. aspersa near Dropmore, on the Bucks side of the 

 river.— r. D. A. Cocke re I I. 



Hydrozoa and Polyzoa.— The name of the illus- 

 tration in your September number should be P^epralia 

 variolosa. The writer of the paper speaks of the polyzoa 

 and hydrozoa as being closely related, whereas they 

 belong severally to distinct divisions of the animal 

 kingdom ; viz. the hydroida to the crelenterata, 

 while the polyzoa, as lepralia, flustra and others, 

 are allied to the mollusca, a much higher group, and 

 have been placed accordingly in the molluscoida (a 

 subdivision of mollusca), including these (polyzoa), 

 and the tunicata (ascidians, &c.). The author 

 (P- 193) quotes Johnston as an authority in placing 

 lepralia in ascidioitla. More recent writers, as 

 Busk and Hinks (British Polyzoa, 1S70), and many 

 others, separate lepralia and allied genera from the 

 ascidians, although they admit a relationship between 

 them which I may illustrate thus : 



Molluscoida. 



I I. . 



I. — Polyzoa. 2. — Ascidioida. 



The polyzoa being members of the suborder mol- 

 luscoida, and only allied laterally to ascidioida. 

 Referring to the mode of growth of these organisms, 



