374 PROCEEDINGS OF THE AMERICAN ACADEMY 



chusetts Bay. — The Ceramtum arachnoideum ? Ag. of the Nereis Am.- 

 Bor. is not the true species of Agardh, to whom I showed American 

 specimens. The species so designated by Harvey is not uncommon on 

 tlie New England coast; but what it really is, whether peculiar to 

 America or a European species also, must remain in doubt. 



311. Ceramium byssoideum, Harv. Key West. 



312. Ptilota densa, Ag. California. 



313. Ptilota htpxoides, HaVv. (inc. P. Oalifornica, Rnpr. 

 partim). — This species was first described in 1841 by Harvey in the 

 botany of Beechey's Voyage. In the Nereis Am.-Bor., Harvey also 

 describes a Ptilota Californico, Rupr., with a variety concinna. 

 Through the kindness of Prof. Wright, of Dublin, I was enabled to 

 examine the specimens of the last-named species and variety in the 

 Harvey Herbarium. 



Strange to say, the P. Callfornica of Harvey's Herbarium con'e- 

 sponds precisely to the description and plate of P. hypnoides, while the 

 variety co7icinna is quite different and more closely related to P. plu- 

 mosa. Furthermore, the var. concinna is not the P. concinna of the 

 Rodgers and Ringgold Expedition. There can be little doubt that 

 P. hypnoides and P. Callfornica, exclusive of var. concinna, sliould be 

 united. The question is, Which name has the priority? There is no 

 reference to P. Callfornica either in Postels and Ruprecht's Illustra- 

 tiones or in the Ph3'Cologia Ochotensis, and I cannot ascertain when 

 or where it was ever published by Ruprecht. On the supposition that 

 it was first described by Harvey in the Nereis Am.-Bor., the name 

 P. Callfornica should give place to P. hypnoides of Beechey's Voyage. 



The position of the var. concinna is difficult to define. I saw in 

 the Ruprecht Herbarium at St. Petersburg specimens labelled P. 

 filicina, which were evidently the same as the var. concinna. If I am 

 not mistaken, P ^/te^rtrt was never 2:)ublished by Ruprecht. After a 

 careful comparison of Californian specimens with authentic specimens 

 of P. jo^umosa presented by Prof. Agardh, I venture to express the 

 opinion that P. Callfornica, var. concinna, of the Nereis Am.-Bor., is a 

 variety of P. pJumom ; and, not to confuse it with the specimens of 

 Rodgers and Ringgold's Expedition, distributed under the name of P. 

 concinna, I would propose the name P. plumosa, var. filicina. This 

 variety differs from the type in being more regularly pinnate and of a 

 thicker substance. Fragments of the base look like a distinct species ; 

 but examination of the tips and younger undenuded parts of the frond 

 show that they are not specifically distinct from P. plumosa. The 

 specimens distributed with Hall's Oregon Algx as P. pectlnata, Harv., 



