102 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



have arisen in regard to this genus by showing that various species 

 recently assigned to Ophiothamnus do not possess the characters of 

 that genus at all, while others, assigned to different genera, must be 

 considered as true species of Ophiothamnus. 

 He places in this genus the following species : 



Ophiothamnus vicarius Lyman. 

 Ophiothamnus affinis Ljungman. 

 Ophiothamnus remotus Lyman. 

 Ophioleda minima Kcehler. 

 Opliiomitra habrotata H. L. Clark. 

 Ophiothamnus venustus Matsumoto. 



The other species assigned to the genus Ophiothamnus are placed 

 by Matsumoto in the new genus Ophiurothamnus, which is repre- 

 sented in the Albatross collection by two species, which I shall con- 

 sider shortly. 



From the enumeration of the species given above it is seen that 

 Matsumoto places in the genus Ophiothamnus, Ophioleda minima, 

 which I had at first placed in the genus Ophioplinthaca, and for 

 which I had later believed it necessary to create the genus Ophioleda. 

 According to Matsumoto, Ophioleda is a synonym of Ophiothamnus. 

 As the learned Japanese naturalist has given some notes on the 

 internal structure of this last genus, I wished to compare with it 

 the structure of Ophioleda minima. Unfortunately, because of its 

 small dimensions, and especially because of the small number of in- 

 dividuals which I have at my disposal, it has not been possble for 

 me to obtain a sufficient number of preparations to allow me to de- 

 cide whether the genus Ophioleda should be retained or should be 

 considered as a synonym of the genus Ophiothamnus. I therefore 

 provisionally leave the question open, regarding as very plausible 

 the union proposed by Matsumoto. 



Genus OPHIUROTHAMNUS Matsumoto. 



Notes. Speaking of the genus Ophiothamnus, Matsumoto ('15, 

 p. 63) remarked, as I have stated above, that certain species assigned 

 to this genus did not accord entirely with Lyman's conception of it, 

 or with the type that he had chosen. He notes especially Ophio- 

 thamnus exiguus (Lyman), O. laevis Liitken and Mortensen, and O. 

 stultus Kcehler as species which should not have been assigned to 

 Ophiothamnus. I have profited by the opportunity which I have had 

 to study again a specimen of Ophiothamnus stultus with a view to 

 determining the question, and I have arrived at this conclusion, con- 

 formable with Matsumoto's view, that it is necessary to create, in 

 addition to the genus Ophiomitrella, a new genus in which Ophio- 

 thamnus stultus Kcehler and Ophiomitra dicycla H. L. Clark, as 



