ARCA. 183 



Algiers showing the transition of one of these species 

 from the other. 



The accentuation of the name tetragona has also 

 perplexed many conchologists. There is no question 

 that, if it were formed into a Latinized-English word, 

 the accent would lie on the second syllable, as is the 

 case in pentagonal and hexagonal, and Dr. Latham was 

 quite right in saying that English quantities are not 

 Latin quantities. Bnt tetragona being a Latin word, it 

 seems to me that the classical mode of accentuating 

 words written in that language, according to their 

 correct or accustomed quantity, ought to be used in 

 pronouncing such names as the present. This name 

 being derived from ycovla " an angle," and having 

 been adopted by the Romans, as well as the Greek 

 combination of the same root with other numerals, the 

 penultimate syllable is long, and I have therefore placed 

 the accentuating mark over it. 



I have now before me the original specimen of Turton's 

 A. reticulata, which he said was found in Lough Strang- 

 ford by his son-in-law, Dr. Macgee. It is not the A. 

 reticulata of Grmelin, but the A. bar bat a of Linne, and is 

 a rather common Mediterranean shell. Mr. Dillwyn 

 gave me two single valves, in a much worn state, received 

 by him from Miss Hutchins, as having been collected by 

 her in Bantry Bay, and which he sent to Montagu for 

 his inspection. The paper in which they were wrapped 

 still bears the name " A. barbata " in the handwriting of 

 the latter naturalist. I do not consider this evidence 

 sufficient to include the species among our indigenous 

 mollusca. Collard des Cherres, however, has enumerated 

 it in his list of shells living on the coast of Brittany, and 

 it may therefore be looked for in the Channel Isles. 



The Turtonian collection also contains a specimen of 



