TRANSACTIONS OF THE SECTIONS. 147 



Fam. IV. Diastoporidse, Busk. 



Gen. 5. Ai.ecto, Lamx. 



1. Alecto major, Johnston. A. major, Johnston, Brit. Zoophyt. ed. 2. p. 281, pi. 49. 

 figs. 3, 4. 



2. A. granulatu, M.-Edwards. A. granulata, Johnston, Brit. Zooph. ed. 2. p. 280, 

 pi. 49. figs. 1,2. 



Gen. 6. Discoporella, Gray. 

 1. D. hispida, Fleming (sp.). Tubulipora hispida, Johnston ; Busk. Discopora his- 

 pida, Fleming. 



Gen. 7. Patineixa, Gray. 

 1. P. patina, Lamarck (sp.). Tubulipora patina, Lamarck; Johnston; Bisso; 

 Blainville ; 8(C. 



Suborder III. CTENOSTOMATA. 



Fam. I. FarrellicUe, Busk. 



Gen. 1. Avenella, Dalzell. 

 1. A. fusca, Du Gell. Farrella fusca, Busk. 



Gen. 2. Buskia, Alder. 

 1 . B. nilens, Alder. B. nitens, Alder, Zoophytes of Northumberland S,- Durham, p. Go", 

 pi. 5. figs. 1, 2; Busk. 



Remarks on the Molluscu of Aberdeenshire. By Dr. Dickie. 



These remarks are founded on the investigations of the late Professor Macgillivray, 

 and my own observations. 



The Mollusca of Aberdeenshire comprehend representatives of all the British 

 families, excepting eleven ; the species amount to two hundred and thirty. 



Although some objections have been urged against the types into which the 

 British species are divided in Forbes and Hanley's 'Mollusca,' they, however, 

 afford a useful scale of comparison, as to distribution on different parts of the coast 

 of the United Kingdom. 



Of the Lusitanian and S. British types, the best-marked example found here is 

 Ti-ochus crassus, which is rare. The European type is well represented ; but some 

 species, very abundant in more southern and western districts, are rare at Aberdeen. 

 The Celtic ' type, like the last, is general, but principally distributed toward the 

 north : many of its species are abundant at Aberdeen ; but some are rare, as Chiton 

 ruber and Pholas Candida. The British type consists of a few species most abundant 

 in, or confined to Britain : two of these are frequent on this coast, viz. Trochus 

 millegranus and Pecten tigrinus ; Astarte triangularis and Scalaria Trevellyana are 

 rare. The Atlantic branch is very partially represented here ; and the few species 

 which occur are rare. The Boreal type does not comprehend many species ; but 

 most of them are found on our coast, and are generally abundant, as Astarte com- 

 pressa, Acnicea testudinalis, Cyprinu Islandica, Trochus helicinus, Velutina flexilis ; 

 others are rare, as Astarte elliptica, Puncturella Noachina, &c. Those designated as 

 truly Arctic in the British list are few ; none have hitherto been found here. 



Our mountains are singularly deficient in land- and freshwater-species ; I have 

 only seen three at any great elevation. Pisidium pulchellum occurs at 1742 feet, 

 along with Limneus pereger, the shell of the latter being very thin and fragile, and 

 the tip of the spire usually defective ; the Pisidium is also found at 2400 feet. The 

 other species observed above 1000 feet is Arion ater, viz. at 1874 feet, the indi- 

 viduals being large, and the colour well-developed. 



It may, finally, be worthy of record here, that Panopaa Norvegica and Tellina 

 proxima occur in the glacial clay in Belhelvie. 



On the Structure of the Shell in some Species of Pecten. By Dr. Dickie. 



The following brief statement of facts is not brought forward with any intention 

 of calling in question the more important conclusions regarding shell-structure in 



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