W. G. Van Name — Bermuda Ascidians. 359 



The spicules are very large, often ,l mm in diameter, with numerous 

 long conical or somewhat flask-shaped points. They are chiefly con- 

 fined to a layer lying about .5 mm to l mm below the upper surface. 

 In this layer they are abundant and placed near together. 



The zooids are placed close together and mostly nearly perpen- 

 dicular to the surface. They are rather large (the specimen figured 

 (fig. 35) measured 1.6 mm long) and rather dark in color, due to brown 

 pigment in the mantle, especially about the branchial aperture, and 

 to a less extent on other parts of the thorax. The lining of the 

 branchial siphon is particularly dark colored. 



Thev have about sixteen stigmata in a row on each side. In 

 several different individuals I found the number of turns in the 

 spiral portion of the oviduct to be about eight. Herdman gives four 

 or five as the number in his specimen. 



The locality of the type of this species, described in the Challen- 

 ger Report, is given as doubtful, but probably just south of the Cape 

 of Good Hope, in 150 fathoms. 



Only two specimens of this species were found at Bermuda, 

 neither of them as large as the type specimen. One was obtained in 

 1898, the other in 1901, but the exact localities are not recorded. 



Didemnum atrocanum, n. sp. 



Plate LI. Figures 30 and 34. Plate LIX. Figure 114. 



This species forms very thin incrusting colonies. The largest 

 that were obtained measure 2 ,nm thick and from 30 mm to 40 mm 

 across. In consistency it is gelatinous, and the spicules are not 

 sufficiently abundant to greatly alter the character of the test. 



The spicules are of moderately large size, averaging over .05 ram in 

 diameter, but differ somewhat from those of D. savignii in having 

 more numerous points, which are generally somewhat shorter and 

 more or less irregularly rounded or split or broken at the extremities, 

 though some have the regular conical or flask-shaped points, as in 

 the last named species. They are irregularly distributed in the 

 interior of the colonies, being thickly crowded in small patches and 

 absent in other places. Where they are dense their white color 

 makes them noticeable against the grey or blackish yet transparent 

 test. Many bladder cells also occur. 



The zooids are not on an average quite as large as those of the 

 last described species (D. savignii). In many of the specimens the 

 mantle cells contain so much black pigment that the whole colony 



