MUSEUM OF COMPARATIVE ZOOLOGY. 51 



involuted and the tentacles concealed. In this condition the upper extremity 

 is covered with convergent, strongly raised folds or crest-like ridges, larger and 

 smaller ones irregularly alternating. These crests correspond in number to the 

 tentacles, and run up somewhat on their outer ba^es; the larger ones, which 

 correspond to the inner or primary tentacles, can be traced inward between the 

 outer tentacles, until they run to and coalesce with the external basal portion 

 of the inner ones. The upper portion of the column, covered by these ridges 

 and crests, is strongly differentiated from the part below it, for its integument 

 is soft and lubricous, and usually decidedly red or pink in color during life; 

 this portion, in fact, like the tentacles, secretes an abundant mucus, which is 

 strongly phosphorescent. A row of large rounded warts or tubercles, or a 

 more or less marked, transverse, verrucose ridge separates this upper or sub- 

 marginal zone from the general surface of the column, which is firmer, more 

 or less verrucose, and generally wholly or partly covered with a dirty brovvm- 

 ish, somewhat chitinous, tough and firmly adherent coating, which is strongly 

 wrinkled in contracted specimens, and sometimes has hydroids, bryozoa, and 

 even such shells as Anomia adhering to its surface. This covering is often 

 partially, and sometimes wholly wanting, especially in very large examples. 

 It often persists on the larger upper verrucse, even when absent elsewhere, and 

 in some rather exceptional specimens it is much thickened on these warts, or 

 even forms for them hard conical tips, sometimes affecting thus only the upper- 

 most row, but at other times several series of them. 



The most common form (Fig. 6) in expansion has the body more or less 

 cylindrical, varying to hour-glass shape. The base may be broad and flat, 

 often much broader than the body, and adherent to stones and shells; it may 

 closely clasp cylindrical worm-tubes, branches of gorgonice, etc.;* or it may 

 be deeply concave and bulbous, and enclose a mass of sand and mud.f Speci- 

 mens with these different styles of base may all occur in the same locality, 

 without other corresponding differences. 



The column is covered with hard, prominent, and persistent verrucae, ar- 

 ranged in pretty regular vertical and transverse rows, the upper ones becoming 

 larger and more prominent, often with a hard, sharp tip, the lower ones grad- 

 ually diminishing. At a short distance below the upper edge there is a trans- 

 verse ridge, or row of large tubercles, above which the character of the tubercles 

 and of the integument abruptly changes, the rounded verrucae being replaced 

 by longitudinal ridges and crests, alternately larger and smaller. In other 

 cases the verrucae become nearly obsolete below the middle, or are indicated 

 only by longitudinal and transverse wrinkles. In very large examples the 



* This habit is still more common with several ot4ier species from the same 

 localities. Among these are Actinauge nexiUs V., Sagartia ubyssicola, S. Acanelke . 

 v., etc. 



t These enclosed masses of bottom often afford us accurate data as to the pre- 

 cise nature of the bottom sediments, with the relative proportions of mud, sand, &c. 

 in their original condition, for this matter is clasped so tightly tiiat no part can 

 wasii out. 



