36 



THE ANATOMY OF THE BRITISH SPECIES OF THE 

 GENUS SOLEN. Pt. i. 



By H. H. BLOO.MER. 



(Plates ii — iii.) 



In working at the anatomy of the various British species of the genus 

 Solen, I was somewhat surprised to find that, while S. ensis and »S. 

 siliqua are in their structure very -similar to each other, they differ 

 very materially from ^. marginatas, the latter exhibiting many points 

 of interest. Apart from this, Solen also presents many interesting 

 features when compared with other types of the Pelecypoda. Further, 

 on looking through the literature, I have failed to find any work 

 dealing fully with the anatomy of the genus. Menegaux^ has described 

 at length the circulatory system, and Pelseneer,- Barrois,'^ Lang,* 

 Faussek^ and others, have made reference to other portions of the 

 anatomy, but have not dealt systematically with it. 



There are four species of Solen recognised as British, viz., S. ensis, 

 L., S. siliqua, L., {S. marginatus, Pult. and Don. or S. vagina, L.), 

 and S. pellucidus, Penn. In the latest classification, ejisis and siliqua 

 are placed in the genus Ensis, Schum., pellucidus in the genus Cultellus, 

 Schum., leaving only one species, marginatus or vagina, in Linne's 

 genus Solen. I purpose dealing with this question in a later paper. 



It is my intention in the present paper to deal with the external 

 characters, the musculature, and the alimentary canal of the first three 

 species, and in a future contribution to complete the anatomy of the 

 same, and the whole of the anatomy of S. pellucidus. 



I desire to express my thanks to the Council of the Birmingham 

 Natural History and Philosophical Society for the grant they have 

 made me towards defraying the expenses in connection with this 

 work ; also to Mr. Walter E. CoUinge for the kindly advice he has 

 extended to me. 



External Ch.\racters. 



Solen ensi", L. (PI. ii, fig. 2). 



S. ensis is an elongated animal, measuring in length from six to 

 seven times the measurement from the dorsal to the ventral surface at 



1. Recherches sur la circulation des Lamellibranches Marins, pp. 170, Besangon, 1S90. 



2. Introduction k r<5tude des Mollusques, 1804. 



3. Revue biol. du Nord dc la France, 1890, T. ii, pp. 209 — 229, 299 — 311, 351, 356. 



4. Text book of Comparative Anatomy, 1896, pt. ii. 



5. Trudui St Peterb. Obshch., x.wiii, pp. 213 — 270, 2 pis. 



