4 McMURRICH 



that in employing the specific term diantJius, I do not desire to 

 imply any prejudice to the claims to priority of two other terms, 

 namely \\\^ fclinuin of Linnaeus and the pentapetala of Pennant ; 

 I have not access at present to the works in which these terms 

 were first used, and cannot, therefore, decide as to their validity. 



Habitat. — I find in the present collection several representa- 

 tives of this species, the majority of which were collected in 

 shallow water principally from the piles of wharves or from 

 stones, two specimens only coming from deeper water, one 

 from 9. 5 meters, where it was adherent to a deserted clam shell, 

 and the other from 13.7 meters. 



External Form. — Allowing for differences plainly due to size 

 and degree of contraction, the external form is essentially the 

 same in all the specimens. The base is adherent and the 

 column is essentially cylindrical and smooth, except for, in 

 some cases, fine longitudinal or transverse ridges, evidently due 

 to contraction. A short distance below the margin there is a 

 well-marked circular fold or collar, above which the wall is 

 considerably thinner than it is below, and scattered over the 

 surface below the collar, cinclides may be observed. 



The margin is distinctly lobed and is tentaculate, the tenta- 

 cles being very numerous and closely crowded in many cycles. 

 They are rather short, and acuminate and entacmaeous ; I do 

 not find, however, that the relative length and thickness of the 

 tentacles is the same in all the specimens, differences of contrac- 

 tion causing them in some cases to be rather conical in shape, 

 while in others they are much more slender and almost filiform. 

 The disk is smooth and slightly concave, the mouth being some- 

 what prominent. The lips appear to be tuberculate, this appear- 

 ance being due to the continuation upon them of the longitu- 

 dinal ridges which occur upon the stomatodaeum. In all the 

 specimens in which the mouth is visible two gonidial grooves 

 can be distinguished, except in one specimen in which there 

 seemed to be only one. 



Color. — Dr. Calkins' notes of the various specimens show 

 that they can be arranged in three groups according to the pre- 

 vailing color. Thus there is a group (I) in which the column 



