ON MARINE AVOOD-BORING ANIMALS. 



391 



21. Notes on Marine AVood-boring Animals. — I. The Sbip- 

 worms (Teredinidse). By ^Y. T. Calman, D.Sc. 



(Submitted for Publication by permission of the Trustees of the British Museum.) 

 [Received April 27, 1920 : Read .June 1, 1920.] 

 (Text-figures 1-11.) 



The specimens discussed in this paper were collected, for the 

 most part, on behalf of a Committee appointed by the Institution 

 of Civil Engineers to inquire into the deterioration of structures 

 exposed to sea-action. This Committee, at my suggestion, re- 

 quested its correspondents at various seaports to send in speci- 

 mens of animals damaging the timber of harbour works. The 

 result has been to get together a collection of very considerable 

 importance, both from the point of view of the practical engineer 

 and from that of the scientific zoologist. A set of the specimens 

 will be placed in the Museum of the Institution of Civil 

 Engineers, and tlie remainder have been presented by the 

 Committee to the British Museum (Natural History). I desire 

 to express my sense of obligation to the members of the Com- 

 mittee, more especially to the Chaii-man, 8ir William Matthews, 

 K.C.M.G., aiid the Secretary, Mr. P. M. Crosthwaite, as well as 

 to the various harbour engineers named below, by whom the 

 specimens were collected and preserved. 



In dealing with the Teredinidae I trespass with reluctance on 

 the domain of the malacologists. It is only the impossibility of 

 linding a student of Mollusca ready to undertake the description 

 •of the collection that leads me to publish these notes, to which, 

 however, the very accurate figures drawn by Miss G. M. Wood- 

 ward may give some permanent value. I am indebted to my 

 colleagues, Mr. B, B. Woodward and Mr. G. C. Robson, for much 

 guidance and help in exploring the literature and in examining 

 the Museum collections of Mollusca. 



Many writers h^ve commented on the difficulties that stand in 

 the way of a systematic study of the Teredinidae. The lack of 

 agreement as to the characters to be regarded as generic is 

 strikingly shown in the recent synonymy of several species, while 

 the inconstancy of speciHc characters drawn from the valves of 

 the shell was commented on long ago by Forbes and Hanley 

 (Hist. Brit. Mollusca, i. p. 87 (184*8)). These difficulties I cannot 

 pretend to have solved, but some general considerations suggested 

 hy study of my mateiial inay be worth recording. 



The changes in form of the shell-valves during growth seem to 

 have received little attention, although several writers mention 

 the obvious fact that the number of the striae on the anterior 

 «,nd antero-median divisions of the valves increases with age. 

 Together with this, however, there goes on a resorption of the 



