448 THIRD REPORT— .] 833. 



On the Naturalization in England of the Mytilus crenatus, a 

 native of India, and the AcematichaGrus Heros, a native of 

 Africa. By Charles Willcox, Curator of the Museum of 

 the Portsmouth and Portsea Literary and Philosophical So- 

 ciety. 



Mr. Willcox states that when His Majesty's ship Wellesley 

 was docked at Portsmouth in July 1824, he discovered on the 

 lead of the cutwater and under the keel a great number of My- 

 tili, which, on examination, proved to belong to the species 

 named M. crenatus. The Wellesley was launched at Bombay 

 about February 1815, and came into this harbour in May 1816, 

 where she remained for upwards of eight years previously to her 

 being taken into dock. 



The same species of Mytilus has, however, within the last 

 twelve months, been found by Mr. Willcox among groups of 

 Mytilus edulis, on the fore part of the keel of several ships on 

 being taken into dock, which proves their naturalization in a 

 climate apparently uncongenial to their nature. 



The AcematichaGrus Heros has been found in many parts of 

 His Majesty's dockyard at Portsmouth for some years past. 

 Several specimens are in the possession of Mr. Willcox, and al- 

 though it was generally supposed that they were bred in African 

 timber, imported for the building and repairs of the navy, yet 

 it was not until the following circumstance occurred that this 

 fact was proved. With the intention of determining this ques- 

 tion, Mr. Willcox had for a considerable time been in the habit 

 of examining every piece of African timber which came under 

 his inspection : at length, whilst a piece of this timber was be- 

 ing cut, several small holes, the size of a pea, were discovered 

 running in a direction more or less oblique to the fibres of the 

 wood, and generally increasing to six or seven times their dia- 

 meter at the orifice, the inside surface being perfectly smooth. 

 Shortly after, a larva was found surrounded by the dust of the 

 wood, and it was carefully extracted from one of these holes. 

 This circumstance encouraged Mr. Willcox to make further 

 search, and he at length succeeded in finding in another hole 

 the pupa, which was taken out alive, and he found it to be that 

 of the insect before mentioned. 



The perfect insect was kept alive by Mr. Willcox nine weeks, 

 by feeding it on sopped bread sweetened with sugar. Several 

 of these insects have of late been found in an apparent healthy 

 state, at different parts of the island of Portsea ; two of them 

 (male and female) Mr. Willcox has now alive. It may be, per- 



