^'m)^''] PROCEEDINGS OF THE NATIONAL MUSEUM. 173 



ment seems to saturate the alcohol ({ui(;kly, fresh alcohol coiiti lining- to 

 extract more of it even after several cliaugings. 



The base is thin, allowing the mesenteries to be seen through, when 

 the more or less membranous brown coating which covers it is re- 

 moved. The margin of the base in all the specimens is concealed by 

 the limbus being reflected over it. 



The c()lnmn is whites the ectoderm liaving been entirely removed, 

 and is irregularly corrugated; no tubercles or verrucic are present, 

 however. The mesogloea is very thick, measuring in one specimen at a 

 point a short distance aboNO the limbus as much as 3.5""" in thickness. 

 It is not, however, harsh or resistant to the touch, but; on the contrary 

 is rather soft, and in structure is almost homogeneous or hyaline, with 

 small ci^lls scattered through it. Towards its ui)pei'])artare a number 

 of ridges, Avliich are hollow and thin-walled, and pass to the bases of 

 the tentacles of the outer row. The sphincter muscle extends a con- 

 siderable distance down the column wall (PI. xxvii, Fig. (15), but is 

 throughout thin. It lies throughout its entire extent close to the endo- 

 dermal surface of the mesoghea, x>'issing into the circular musculature 

 of the column wall. Above it is very slightly thickened, but not at all 

 as in Faracfis. The nuiscle cavities for the most part show little ten- 

 den(;y towards any regular arrangement (PI. xxvii, Fig. 60), though 

 towards the lower edge of the muscle thoy are somewhat elongated, and 

 arranged in lines nearly perpendicular to the surface of the mesoghea. 



Tiie margin is tentaculate. The tentacles are arranged in four cycles, 

 12, 12, 24, 18. The ridges upon the upper surface of the column run to 

 the bases of the outer tentacles, and from the bases of the inner ones 

 ridges extend outward, but only for a short distance, losing themselves 

 before they reach the outermost cycle of tentacles. The mesoghra of 

 the bases of the tentacles is only very slightly thickened, and the longi- 

 tudinal muscles of the tentacles are imbedded in the mesoghea. In the 

 disc the radial muscles are mesogheal and are arranged in a very char- 

 acteristic manner (PI. XXVIII, Fig. 68), recalling wlmt Hertwig hasfigured 

 for DyHactiH craHsicornu. Oi)posite the insertions of the mesenteri(\s 

 into the disc the radial musculature is interrupted so that it is di- 

 vided into radial bands, each separated from its neighbors by a depres- 

 sion on the surface of the disk. Each radial ban<l appears to be a 

 single flattened cavity, traversed by perpendicular, somewhat branch 

 ing, fine trabecuhe of mesogioea, which divide the large cavity into a 

 greatnumber of smalhu" ones, in which lie the muscle cells. 



The stoinatodicum is h)ngitudinally ridged ami is continued down- 

 wards almost to the base. The siphonoglyphes are deep, and lu'ar 

 their lower extremities two transverse folds, lying one above the other, 

 project across the cavity of each, closing it below. 



The mesenteries are arranged in ninety-six pairs, the youngest cycle 

 of forty-eight pairs being indistinguisluible to the naked eye. Tiie 

 twelve pairs of the first two cycles are perfect, the twelve tertiaries 



