62 C. McLEAN FRASEE 



axis of the stem or branch. In some cases there is a slight indica- 

 tion of flaring, but this is seldom noticeable. The hydrothecae 

 are immersed to a large extent, less than one-fourth being free. 

 The operculum consists of a single adcauline flap. 



Gonosome. — The gonangia are borne on the upper surface of 

 the branches. The shape is an elongated oval, with a distinctly 

 narrowed pedicel. At the distal end it narrows suddenly to form 

 a narrow collar which is double, on account of the margin being 

 turned in. A finely-toothed ornamentation appears on the col- 

 lar. The gonangia are very similar to some of those found on A. 

 ahietina. 



Disfrihution.—Alhatross Station 2865, N. 48° 12', W. 122° 51', 

 48 fathoms (in collection of the State University of Iowa) ; San 

 Juan Archipelago. 



This species resembles to some extent, one of the varieties that 

 Clark includes under Sertularia variabilis,*^ but in this species 

 he has included forms resembling such greatly differing species 

 as Ahietinaria trasJci and Ahietinaria ahietina. It seems to me 

 that even if there are intergrading forms, such distinct typical 

 forms should be treated as specifically distinct. It is a common 

 experience in examining a large amount of material, to find many 

 speciipiens showing such intergradation between two allied spe- 

 cies, that it is difficult to decide to which they belong. As such is 

 the case, distinct types must be treated as specifically distinct, no 

 matter how much intergradation there may be, if we are going 

 to have any classification. The indications are that if it were 

 possible to get even a fairly complete collection of hydroids, or 

 of any of the lower marine groups, the whole group would be a 

 series of gradations, and not only that, but the groups them- 

 selves would scarcely be delimited. Even in the higher land 

 forms, where isolation has had the best chance to produce dis- 

 tinct species, disagreement among systematists as to the position 

 of a specimen, often occurs. 



This type is plentiful in the San Juan Archipelago, and is so 

 characteristic, that it can readily be picked out from a hydroid 

 mass, without the aid of a lens. Since this is the case, even if 

 intergradations may be or have been found between it and other 

 forms, it seems best to distinguish it specifically. 



■i'-> Alaskan Hydroids, 1876, p. 221. 



