NO. 1923. DESCRIPTIONS OF PACIFIC ALCYONARIA— NUTTING. 11 



As before stated, Helicoptilum rigidum, representing a new genus 

 and species, was secured at a depth of 2,700 fathoms off Bering Island. 

 So far as the writer has been able to ascertain, this is the g]:eatest 

 depth from which an alcyonarian of any kind has thus far been 

 dredged. This form is also unique among the Pennatulacea oa 

 account of its extreme rigidity, being possessed of an exceedingly 

 dense and heavy axis cyhnder with a remarkably compact cortex 

 of spicules. 



No specimens were secured between the extreme depth just men- 

 tioned (2,700 fathoms) and 1,766 fathoms where two previously 

 described species were secured as noted on page 7. 



SYSTEMATIC DISCUSSION OF THE ALCYONARIA SECURED BY THE. 

 U. S. FISHERIES STEAMER "ALBATROSS " DURING ITS CRUISE IN 

 THE NORTHWEST PACIFIC IN 1906. 



Order ALCYONACEA Verrill. 



Polyps single or in fixed colonies, without an axis cylinder. 



Family CORNULARID^ VerrUl. 



Polyps united by solenia; colonies sometimes forming lobular 

 encrusting masses, sometimes branching through new polyps budding 

 from the sides of older ones. 



Genus CLAVULARIA Quoy and Gaimard (modified by 



Nutting). 



Spicules present. Colonies consisting of band-like stolons, from 

 which the polyps arise singly, or of branched forms arising from a 

 stolon-like or encrusting base.^ 



CLAVULARIA DISPERSA Kiikenthal. 



Clavularia dispersa KxjkenthaLj Japanische Alcyonaceen, 1906, p. 18. 



Colonies growing on very dark-colored worm tubes, broken, the 

 largest fragment being 15 cm. long; but the worm tube is 9.2 cm. 

 longer. The colony rather thinly encrusts the tube, which, with the 

 alcyonarian, is about 4 mm. in diameter. The polyps are dis- 

 tributed without any regularity whatever, sometimes being in clumps 

 or clusters, and at others being as much as 6 mm. apart. 



The calyces are tubular or conical, a typical one being 3 mm. in 

 height and about as broad at base as high, theifr walls filled with 

 rather slender spindles 1 mm. long and longitudinally arranged. 

 Sometimes there are 8 longitudinal corrugations on the calyx walls, 



1 C. C. Nutting, Descriptions of Hawaiian Alcyonaria, Proc. U. S. Nat. Mus., vol. 34, p. 653. In this paper 

 and another on Alcyonaria of the Californian coast (same publication, vol. 35, pp. 681-727) the writer gives 

 short diagnostic definitions of families and genera. In the present work these definitions will be used so 

 far as they appear to the writer to be satisfactory. 



