8ir H. E. Hotvorth—The Western Baltic. 455 



Scrobictclaria alba. fSctxicava rugosa. . 



Solen pellucida. '\Tliolas crispata. 



*Corbula gibba. fP. Candida. 

 *Mya arenaria. Teredo navalis. 



fM. truncata. 



Among these molluscs those marked with an asterisk are common 

 and found in large numbers, while those marked with a dagger are 

 scarce. The remaining species occur sometimes commonly, and are 

 sometimes scarce. Thus say our authors : " When we began our 

 work Teredo navalis was common. It then seems to have become 

 extinct, and afterwards began to occur again. Solen pellucida became 

 similarly uncommon after being frequently found." They attribute 

 the scarce forms to vagabonds which have made their way from the 

 Cattegat into the Bay of Kiel, especially in the embryo stage, and 

 they mention in addition to such casual visitors among the molluscs 

 certain other vagabond marine animals as taken in August and 

 September, 1861, the Coelenterates Bolina alata, Melicertum georgicum, 

 Steenstrupia rubra, and a species of Bourgainvillia, while in 1869 

 a species o{ Bhizostoma Cuvieri found its way there (id., xxiii). 



Petersen, in addition to the molluscs mentioned by Meyer & 

 Mobius from Kiel harbour, also names Cardium exigimm, var. He 

 substitutes Astarte Walhami for Astarte sulcata as given by 

 M. & M., Abra alba for Scrobicularia alba of the same writers, and 

 also adds Scrobicularia plana, a form unknown to Jeifreys, but as he 

 does not quote piperata he possibly tx'eats this as a synonym. Nor 

 does he mention Tellina tenuis and Teredo norvegica. 



In regard to the Gasteropods from Kiel, he substitutes the generic 

 name Acmcsa for Tectura, in which he seems to be wrong (see 

 Jeffreys, iii, 246). He names Velutina Icevigata and V. haliotoidea, 

 both of which are treated as synonyms (ibid., iv, 242), and neither 

 name occurs in the list of M. & M. He apparently substitutes Bela 

 utricula for the Pleurotoma turricula of M. & M. He properly 

 substitutes the generic name Utriculus for those of Cylichna and 

 Amphisphyra of M. & M., and gives the species obtusus while 

 omitting that of hjalinus, M. & M., from Kiel, and he adds to the 

 Bissoas of M. & M. from the same place the species membranacea, 

 octona, and inconspicua. 



Meyer says that his information went to show that virtually the 

 same marine fauna which he described from Kiel also occurs in the 

 harbour cf Flensborg, and he only names one additional mollusc 

 thence. 



This completes our survey of the Mollusca in the Southern and 

 Western Baltic, and it will be seen how rapidly it becomes richer 

 as we get nearer to the sources of ocean water in the west. 



The gradual change in the size of the molluscs which I noticed 

 in the Eastern Baltic as we proceed eastwards is also paralleled 

 in the Western Baltic. Thus Litorina litorea, which in the 

 North Sea has a normal length of 32 mm., in the Kiel Gulf only 

 reaches 27 mm., while Buccinum undatum, which is normally 

 120 mm. long in the North Sea, is only 58 mm. at Kiel and 55 mm. 

 at Travemiiude. Mobius and Heincke have remarked the same 



