24 Mr. T. Davidson on Recent Terebratulse. 



tice of naming species from appendages which give no clue to 

 the major part of the organism is a custom which loads the 

 nomenclature with synonyms, and, from the extreme variability 

 of spines in the same species, can only bring with it very ques- 

 tionable advantages. 



The largeness of the object can furnish no reason for confer- 

 ring on it a name ; and we might with as much propriety give 

 names to the spines of Micraster or Galerites : those names 

 would, when the test was found, be just as much entitled to 

 priority ; in a natural-history point of view they would be no 

 more objectionable. The only argument for naming the larger 

 object is convenience. But the circumstance of the test not 

 having been found is an evidence of the rarity of the species, 

 and therefore of the little inconvenience which would result 

 from its not having a name. 



The names already given to spines can only be considered as 

 provisional, — to be adopted if the first discovery of the test shall 

 be made with them in situ, but to become synonyms if the test 

 shall be separately named. 



One specimen of Diadema Bonei from Warminster, measuring 

 more than an inch over, with the apical opening broken, has twelve 

 or thirteen ambulacral tubercles. The interambulacrals number 

 twelve, and have secondary rows of nine. It thus only differs 

 from the diagnosis of D. Barretti in having in the areas respect- 

 ively half the number of rows of intervening granules. Another 

 and perfect specimen appears to have but eight tubercles in the 

 interambulacral rows. 



I have seen a single specimen of an internal cast of what was 

 probably a large Micraster, nearly resembling M. cor-anguinum. 



An elevated species of Salenia occurs. 



One species of Astrogonium and 



One species of Pentacrinus. 



III. — On Recent Terebratula3. 

 By T. Davidson, Esq., F.R.S., F.G.S. &c. 



To the Editors of the Annals of Natural History. 

 Gentlemen, 



The important researches as well as the discussions that have 

 taken place, within the last few months, between Mr. L. Reeve, 

 and Prof. Suess of Vienna, in connexion with the recent Tere- 

 bratula, and in which my name has been so prominently brought 

 forward, induce me to 'beg the; insertion of the following ob- 

 servations in a forthcoming Number of your valuable Magazine. 

 In the ninth volume, second series, of the ' Annals' (May 1852), 



