322 Linnean Society. [Feb. 16, 



that the largest tree of this species that he saw was only eighteen 

 feet eight inches in circumference ; but that in Norfolk Island he had 

 measured the largest tree [of Arau&aria excelsa, Sol.] known to be 

 upon the island and had found it to be 187 feet high, the girth at four 

 feet from the ground fifty-four feet, and at twenty feet from the 

 ground fifty-one feet. This tree is hollow for sixteen feet above the 

 ground, but is in good health. 



Read also a memoir " On the Structure and Comparative Phy- 

 siology of Chiton and Chitonellus." By Lovell Reeve, Esq., F.L.S. 

 &c. &c. 



Mr. Reeve commences his paper by remarking on the paucity of 

 species of Chitonidts known to Lamarck so lately as 1819, and the 

 very large number (amounting to between two and three hundred) 

 now known to inhabit the western coast of South America, the shores 

 of New Holland and New Zealand, and other localities explored by 

 recent voyagers ; and states that he is enabled by the kindness of 

 Mr. Cuming and Capt. Sir Edward Belcher to offer a few observa- 

 tions on the structure of Chiton and such remarks on Chitonellus as, 

 in his opinion, will leave no doubt of their claim to generic distinc- 

 tion. He notices the successive additions made to these genera by 

 Mr. Frembly, by Mr. Cuming, by M. Quoy, by Capt. Belcher in the 

 voyages of the Blossom, the Sulphur and the Samarang (and espe- 

 cially in the latter in company with Mr. Arthur Adams), by the Rev, 

 Mr. Hennah, by Dr. DieflFenbach, by Mr. Earl, by Mr. Ronald Gunn, 

 by Mr. Ince, by Dr. Gould, by Mr. Courthony, and by Prof. Edward 

 Forbes and Mr. M' Andrew ; and then enters into an examination of 

 the views of authors with reference to their afiinity, adopting that 

 first promulgated by Adanson and now generally adopted, that they 

 are immediately related to Patella. A description of the animal is 

 then given, and the differences between it and the animal of Patella 

 pointed out, as well as the modifications to which it is subject in 

 different species. The distinctions between the shells and animals 

 of Chiton and Chitonellus are more particularly insisted on ; and the 

 author proceeds to point out a marked difference in the habits of the 

 two genera. He states, on the authority of Mr. Cuming, that while 

 the Chitons live attached to stones and fragments of shells in deep 

 water, or more frequently under masses of stone and on exposed 

 rocks about low- water mark, the Chitonelli dwell in holes and cavi- 

 ties, either of natural formation or bored by other Mollusca, into 

 which they thrust themselves by attenuating their bodies in a sur- 

 prising manner, sometimes turning completely at right angles and at 



