328 Mr. W. Clark on the Pholadidse. 



the animal of one of the rarest of the Teredines and its anatomy. 

 I infer that this genus is still in great obscurity from the serious 

 mistakes that exist in the accounts of it : this is the more re- 

 markable, as it has attracted the greatest attention for the last 

 200 years in consequence of its devastations, which have been so 

 alarming, that various governments have called in the aid of the 

 learned and scientific to examine into their nature, and suggest 

 the best means of preventing its destructive ravages. 



Some authors, amongst them Sir Everard Home, call the 

 external veins the ducts of the testicles, and say the heart is 

 situated near the head. More modern accounts state that there 

 is no true hinge ; that the ligament is obsolete and the foot rudi- 

 mentary or absent ; the branchiae are described as long brown 

 fleshy cords; the elastic stylet is mentioned as a club-shaped 

 body peculiar to Teredo, and the animal is said to be furnished 

 with two stomachs. Some observers say, that the anterior ad- 

 ductor muscle is well marked, but the posterior one slightly; 

 others affirm the branchiae to be the ovaria, and that the protec- 

 tive tube of Teredo megotara is destitute of the posterior circular 

 laminse. I propose to show that not one of these statements is 

 correct. I am informed that M. Deshayes has produced anato- 

 mical details on one or more of the Teredines in his work on the 

 ' Mollusques d^Algerie,^ which I have had no opportunity of con- 

 sulting ; I must therefore abide by my own views. 



The origin of this account is the receipt from Exmouth of a 

 pine stake, which has doubtless served as a water-mark in one of 

 the channels of the estuaries, and being destroyed by the perfo- 

 rations of these creatures, was taken floating in the offing at 

 that place. I received the mass enveloped in sea-weed, accom- 

 panied by bottles of sea-water. The log contained fifty living 

 specimens of this rare species unmixed with any other, many of 

 which were apparently full-grown and 10 inches in length ; some 

 I examined alive and dissected fresh, and many others from spi- 

 rits. These facilities have I think almost put it in my power to 

 produce a tolerably general idea of the animal, though it may 

 not be a complete anatomical detail. Under the circumstances 

 I have stated, I am inclined to think that the following notes 

 may afibrd malacologists some information, and enable them to 

 compare my humble attempt with the anatomies of Teredo by the 

 great masters in this branch of science. Agreeably to my usual 

 method I commence with the external description of the animal, 

 and then proceed to its anatomy. 



Teredo megotara, Brit. Moll. 



Animal vermicular, pale bluish white, inclosed in a subcylin- 

 drical elongated tubular mantle, not of very thin texture, only 



