640 Haddon and Shackleton — A Revision of the British Actinice. 



shell in every case has been entirely removed, but the form in all parts is perfectly 

 preserved by the membranes of the polyps, while the cavity is inhabited by a 

 species of hermit crab [Eupagurus pubescens). Column pillar-like, smallest in the 

 middle, increasing gradually below, but enlarging rapidly at the summit. Walls 

 thin, covered by a layer of closely adhering fine sand. When contracted, the 

 summit is slightly concave ; and in the medium-sized polyps has seventeen, in 

 the largest twenty-four sulcations, radiating from the centre, which is seldom 

 completely closed. Tentacles, forty-eight or more, short, conical. 



The localities at which this species had been obtained up to that time are 

 given by Verrill in 1883, p. 316. The free or type-form (of E. americanus, Verr.) 

 occurred at 28 stations, 28 to 487 fathoms, whereas the incrusting variety 

 " (^— Zoanthtis norvefficus, Kor. & Dan.)" occurred at 11 stations, 69-160 fathoms. 

 The former is by far the most abundant numerically. Later (1885), he gives the 

 bathy metrical range of the free form as " 26—547 fathoms ; generally diffused 

 and very abundant" (p. 534); and of the incrusting variety, " 49—906 fathoms ; 

 abundant "(p. 535). 



Smith and Harger (1874) report this species from off the coasts of New Jersey 

 to the Gulf of St. Lawrence ; the specimens with incrusted shells inhabited by 

 Eupagurus pubescens came from 60—65 fathoms ; while those from 430 fathoms 

 were on stones and on hydroid stems. The figure, which is of a magnified polyp, 

 is of no real value. 



In Verrill's last Paper (1885, p. 60), he says it is mostly commensal with 

 Eupagurus politus, Smith, and E. hroyeri^ very common ; those on grains of sand 

 (free variety) were even more abundant. Some occurred incrusting sponges, 

 shells, hydroids, tunicates, gorgonia, Paramuricea grandis^ pebbles, &c. The 

 original specimens off New Jersey, 30 fathoms, were commensal with E. pubescens. 

 We think it possible that more than one species has been identified by our 

 American colleague as E. americanus. 



Body-tvall (PI. lix., fig. 2). — The incrustations in this species are numerous, 

 and consist for the most part of coarse grains of sand, so that it is difiicult to 

 make out the structure of the body-wall from our sections. The ectoderm is 

 continuous, and is covered by a cuticle, to which diatoms and dark granules are 

 attached. Nematocysts, containing similar granules, are usually abundant in 

 the ectoderm. The incrustations are embedded in the mesogloea throughout its 

 entire thickness, often protruding into the coelenteron. Single cells are oc- 

 casionally found enclosed in the mesogloea ; and lacunse are sometimes found 

 near the union of the mesenteries with the body -wall ; but the mesogloea is for 

 the most part devoid of cell enclosures. The usual endodermal muscular layer 

 is present, being especially well-developed in the upper part of the column. The 

 endoderm is formed by a thin layer of columnar cells of uniform height. 



