340 W. G. Yan Name — Bermuda Ascidians. 



9 



Reproductive organs in or on one side of the intestinal loop. 

 Testes consisting of a number of separate pyriform glands. Vas 

 deferens not spirally coiled. 



This family is none too well separated from the Clavelinidfe. Qn 

 the other hand the adult zooids of this family much resemble those 

 of the Didemnidae, but the last named family has an entirely differ- 

 ent method of budding and is in reality only distantly related. 



Genus Distoma Savigny, 1816. 



Colony generally thick and fleshy. Systems sometimes present. 

 More often both orifices of the zooids open independently on the 

 surface and the zooids are irregularly placed. No calcareous spicules. 



Branchial orifice normally six-lobed. Atrial orifice also with six 

 lobes and placed at the end of a distinct tubular siphon. 



Tentacles often very numerous; in more than one circle. 



Stomach globular. Intestinal loop more or less twisted. 



Reproductive organs on the left side of the abdomen, which is 

 sej^arated fi-om the thorax b}' a more or less elongated and narrow 

 peduncle. No incubatory pouch is present, though the embryos 

 develop under the mantle of the parent. 



The stomach is smooth-walled in the Bermuda forms. 



The zooids in this genus are qtiite elongated, but the mantle is 

 stronglj^ muscular, and in preserved specimens they are apt to be so 

 contracted as to give little idea of their natural shape. This must 

 be taken into account in identifying specimens of these animals. 



For the purposes of illustrating this paper, individuals were 

 selected which were not much contracted. 



Analytical Table of Bermuda species of Distoma, based on the 

 character of the colony. 



A. — Incrusting, but thick. Surface uneven, usuallv slightly raised 

 over the positions of the zooids. Test firm, colorless but rendered 

 more or less opaque h\ included sand and shell fragments, which 

 are usually most numerous immediately about the zooids, forming a 

 sort of capsule. Zooids large, not pigmented. B. capsulatum. 



B. — Massive, rounded, attached by most of lower surface. Upper 

 surface smooth and shining. Test soft and gelatinous, with brown 

 or dusky pigment, yet more or less transparent. Much sand included 

 in lower portions of colony. Zooids rather large with more or less 

 rich brown pigment. B. convexum. 



