BRITISH SILURIAN BRACHIOPODA. 141 



ngreed in every respect with my previously described E. Capewelli ; and at p. 170 of the 

 'Twenty-eighth Annual Report of the New York State Museuna of Natural History,' he says, 

 in his description of his species, " Surface of the shell, except a small space on the umbo of 

 the ventral valve, covered by finely reticulate marking, with elongate, generally hexagonal 

 pits or openings, with thin and sharp ridges between ; these markings vary in different 

 specimens, and also on different parts of the same individual, being generally finest on the 

 cardinal slopes. The small, triangular space near the ventral beak, which is destitute of 

 marking, has the appearance of having been exfoliated ; but since this is an invariable 

 character in all the individuals examined, varying in size with the size of the shell, it is 

 probably dependent upon organic causes." 



All the many English as well as foreign specimens of E. Capewelli I have examined 

 presented the same smooth, triangular space at the ventral beak. 



In his ' Fragmenta Silurica,' pi. 2, Professors Angelin and Lindstrom give several 

 fine illustrations of the external and internal characters of E. Capewelli from Swedish 

 specimens, and amongst them figures of the smooth, triangular space at the beak of the 

 ventral valve. The characters of the interior surface of the beak are also shown, and one 

 of their figures has been reproduced in Plate VIII, fig. 16, in order to help to the better 

 understanding of the internal characters of this remarkable genus and species. 



In the fifth vol., pi. 81, figs. 1, 2, 3, of his magnificent work on the ' Systeme 

 Silurien du Centre de la Boherae,' 1879, Mr. Barrande figures three apparently distinct 

 species of Eichwaldia, which, like E. Capewelli, show a small, smooth, or unsculptured 

 part at the beak of the ventral valve. From his figures the characters of the sculpture 

 differ in all three, and none of them seem identical with our E. Capewelli. It had 

 been suggested to me that the appearance of the sculpture of the surface of E. 

 Capewelli is precisely that of certain Polpoa one is accustomed to meet with in Palaeozoic 

 rocks, a fact that had struck Mr. R. Etheridge, jun., as well as Prof. Nicholson ; but to 

 accept the ornamentation as that of an encrusting Polyzoon we must suppose that the 

 shell had been entirely replaced by the parasite, as sometimes occurs with Hydractinia. 

 Sections, however, show a perfectly homogeneous structure of the whole thickness of the 

 shell. 



Eichwaldia Capewelli occurs sparingly throughout the Wenlock series, but seems 

 more abundant, as far as I can judge from the present state of our information, in the 

 Lower- Wenlock Shales, but it is also not a very rare shell in the Wenlock Limestone of 

 certain places. 



Genus — Triplesia, Hall, 1859. 



At p. 197 of my ' Silurian Monograph ' is a brief allusion to the history and characters 

 of this genus, and I still entertain the opinion that Triplesia should not be regarded as a 



