Dr. W. B. Carpenter on Spirifer cuspidatus. 295 



attenuated tentacles are seen protruding from the mouth of one. 

 Enlarged under a lens. 



Fig. 2. Tentacle of Leucodore, magnified. The organ is in the somewhat 

 contracted condition in which it usually appears when the ani- 

 mal is placed between glasses : a, ciliated gi"oove on the inner 

 surface ; i, cavity of tentacle ; c, blood-vessel. 



Fig. 3. Ciliated parasite attached to a fragment of the tentacle, a. X 700 

 diams. 



Plate XX. 



Fig, 1. Dodecaeeria conchamm, CErst., from a tangle-root, St. Andrews. 



Enlarged under a lens. 

 IH,g. 2. Hook of the same species. X 350 diams. 

 Fig. 3. Extremities of two of the latter : a, of the same specimen ; ft, of 



a developing or somewhat imperfect specimen, x 700 diams. 

 Fig. 4. Bristles from a dried specimen in limestone from Torquay, sent 



by Dr. Bowerbank. X 350 diams. 

 Fig. 5. Posterior hook of a small Sahella saxicava, from a, dried specimen 



in a Balanvs sent by Dr. Bowerbank. X 700 diams. 

 Fig. 6. Thoracic hook of S. saxicava. X 350 diams. 

 Fig. 7. Minute spear-shaped bristles accompanying the latter. X 700 



diams. 

 Fig. 8. Bristles of the same species : a& b, two of the forms met with in 



the thoracic region, the latter being viewed laterally ; c, posterior 



bristle from the dried specimen referred to under fig. 5. X 350 



diams. 



XXXIV. — On the Structure of the Shells of Brachiopoda. 



To the Editors of the Annals and Magazine of Natural History. 



Oban, Sept. 21, 1868. 



Gentlemen, 



On my return from the mission of scientific research into 

 the zoology of the deep sea, with the charge of which I have 

 had the honour to be entrusted by the Admiralty, at the in- 

 stance of the Council of the Royal Society (and the very re- 

 markable results of which will be made public at the earliest 

 possible period), I find the note of Prof. King contained in your 

 last Number, on which I have only to remark that the admis- 

 sion he has cited of the fallacy of his original imputation upon 

 the accuracy of my researches into the sti'ucture of the shells 

 of Brachiopoda is limited to the single case of the recent 

 Rhynchonella psittaxiea^ which did not enter into his original 

 charge, because he had not then examined it. That charge 

 was founded upon his superficial examination of fossil Rhyn- 

 chonellida and Spiriferida ; and neither then nor since has 

 Prof. King made the slightest retractation of it. By declining 

 to reply to my last three questions, he leaves the matter ex- 

 actly where it was before ; so that it must be presumed that 



