130 BULLETIN OF THE 



The stem and the outside of the calicle arc covered with a rough brown 

 skin, which, under the microscope, presents the appearance of a rough, corru- 

 gated reticulation. It contains thin calcareous plates without definite shape, 

 and is very liable to fall off. No muscular fibres could be detected under it. 

 J. Midler denies the power of voluntary motion to the stem of Pentacrinus, 

 on account of the total absence <>t' muscles. In Bourgueticrinus the stem 

 has indeed no great flexibility, but tin- complication of the ligaments of the 

 articulations, ami the hinge-like arrangement of the latter in two alternate 

 directions would seem unnecessary if the motion is to consist merely in a 

 passive swaying to and fro with the oscillations of the water. 



Two specimens have, in place of a calicle, a small conical button, com- 

 pose! of two or three joints. I am not prepared to say whether this is an 

 undeveloped form, or the result of an effort to reproduce a lost head. 



The length of the largest stem obtained is ~>\ inches, exclusive of root 

 and calicle. The smallest and most complete specimen has a stem measur- 

 ing only 1}, inches. This specimen has three small sh lifers adhering to 

 the outside of its calicle. Small round holes, bored probably by these 

 parasitic mollusks, can be seen also on the calicles of some of the other 

 specimens. 



Nephthya nigra room. 



Corallum rising from a membraneous expansion, and forming several 

 small tufts of elongated, costate cells, densely grouped. Every pari filled 

 with spicules: those of the polyp-cells being long, fusiform, and particu- 

 larly numerous in thecostae of the cells. Every corallum bears from 150 to 

 '_"") polyps. Height 1 inch; color black. Rather common oil' Sand Key, 

 Florida, from 120 to 152 fathoms. 



Primnoa verticillaris Ehrbg. 



I refer to this species several branches eight or ten inches long, obtained 

 in 120 fathoms, oil' Sand Key, Florida. Compared with specimens from tin; 

 Azores in the Rlus. Comp. Zoo!., some slight differences in the length of 



the calicles and size of the scales were noticed, but they are not deemed 

 sufficient to warrant a specific separation. 



Primnoa trilopis Poi rt. 



Branches irregularly and sparsely dichotomous, subflabellate. Branchlets 

 very thin and flexible. Calicles in verticils of four, or more generally five, 

 formed of three large cylindrical scales, joined angularly to each other, like 

 the elbows of a stove-pipe. Aperture closed by eight triangular scabs. 

 The distance between tic verticils is equal to or a little less than the 

 length of the single polyps. The cccnenchyma is very thin, and covered 



