W. G. Van Name — Bermuda Ascidians. 371 



ter, and have very short, but often very slender and numerous 

 points, which are usually more or less rounded or broken at the ends, 

 though they may be needle-like. The points are so numerous and 

 short that the spicule appears practically spherical when not much 

 magnified. They greatly resemble those of some forms of the genus 

 Leptoclinum. In life, the colony is of a purer white color than 

 most of the species of Leptoclinum found at Bermuda, but pre- 

 served specimens turn slightly yellowish. 



This species may at once be distinguished from the other members 

 of the family with which it is found associated by the great delicacy 

 of its structure. It breaks or tears at the slightest touch, and is 

 difficult to remove whole from the object on which it grows. This 

 is due to the extensive development of the cavities of the test as 

 already described in Diplosoma. The test is reduced to an upper 

 and lower layer forming the two surfaces of the colony, and a small 

 mass surrounding each zooid, and the fact that it is in all parts quite 

 densely crowded with the spicules renders the thin layers of test 

 substance very brittle. 



The zooids are large (1.5 mm long) and also of very delicate struc- 

 ture. Their apertures are always distinctly visible on the surface of 

 the colony. Their tissues are yellow or orange in color. 



The musculature, both of the mantle and of the branchial sac, is 

 very weak. The muscle bands along the dorsal lamina are dis- 

 tinguishable, but the muscular process is rudimentary, if indeed it is 

 developed at all, and the transverse vessels of the branchial sac are 

 not perceptibly muscular. All the vessels of the branchial sac are 

 very slender. There are about a dozen large stigmata in a row on 

 each side. The tentacles are slender and of at least tAvo sizes; I 

 have not determined the number. 



The stomach wall is exceedingly thin and often becomes folded, 

 but this is probably not its natural condition. 



The reproductive organs resemble those of Diplosoma. 



This is a very common species, occurring under stones near low- 

 water mark at various points about the islands. I found it particu- 

 larly abundant at Waterloo, on Castle Harbor, also at Long Bird 

 Island and Coney Island. 



Genus Echinoclinum, n. gen. 



Test gelatinous, becoming tough and membranous on the surface 

 and about the zouids. The latter are surrounded by a more or less 

 complete calcareous capsule composed of the test spicules. 



