W. G. Van Name — Bermuda Ascidians. 369 



There are four rows of stigmata, with about a dozen in a row on 

 each side. The stigmata are large with very narrow interstigmatic 

 vessels. The transverse vessels are fairly muscular and contract 

 strongly in preserved specimens, as the rest of the branchial sac is 

 very delicate. 



The endostyle is rather narrow. The dorsal languets are long 

 enough to extend more than half way aci'oss the branchial sac. 

 They are tentacular in form. The tentacles appear to be about 

 twelve in number, and are of two sizes placed alternately. 



This species was described by Herdman from a specimen found in 

 shallow water at Bahia, Brazil. 



The large colony here described, which I identify with the Bra- 

 zilian form, was obtained in April, 1901, in Harrington Sound, on a 

 piece of coral. Another smaller colony was obtained off Bailey's 

 Bay a few days later. It was attached to a sponge, and differs in 

 having somewhat smaller zooids, but there seems to be little doubt 

 that both are of the same species. Some of the zooids contain well 

 developed testes and small eggs, but none of those examined con- 

 tained large eggs. Nearly all the zooids in each specimen have 

 buds. 



Diplosoma lacteum, n. sp. 



Plate LIII. Figure 59. 



This species forms small, somewhat flattened colonies measuring 

 10 to 15 nim across and 3 to 4 ram in thickness when alive. The cavi- 

 ties in the test are enormously developed and only a very thin layer 

 of test surrounds each zooid, while the layer bounding the colony is 

 also very thin, so that preserved specimens are generally collapsed, 

 and present a very different appearance from living ones. This is 

 further increased by the fact that in life the test is opaque and of 

 a milky white color which disappears in preservation, leaving the 

 test colorless and transparent. 



There is a little blackish pigment on the zooids, contained in the 

 mantle of the abdomen. The cells constituting the epithelium cover- 

 ing that part of the body are large and flattened, and contain the 

 dark pigment chiefly near the edges, the center being clear and 

 occupied by the nucleus, so that each cell appears as a small dark 

 colored polygon with a clear center. 



The zooids measure at least one-third less than those of the last 

 described species, but do not differ in structure as far as I have 

 observed, except that there appear to be fewer stigmata in a row. 



Trans. Conn. Acad., Vol. XI. 24 February, 1902. 



