No. 429. NOTES AND LITERATURE. 
9 759 
forms a connecting link between two formerly well-differentiated 
families. The species Zygeupolia litoralis is not uncommon at 
Woods Hole, Mass., and because of its transparency would make 
an admirable form for class study wherever the living worms can be 
obtained. Most of the principal features of its anatomy can be 
demonstrated, on the living worm under the low power of the 
microscope. 
The general color of the body appears to be independent of sex 
and of sexual maturity, while that of the intestinal caca depends 
upon the amount and character of the food therein. In external 
appearance the species so closely resembles Micrure ceca, with 
which it is sometimes associated, in size, shape, and color, “that the 
two can scarcely be distinguished withoüt a hand lens which reveals 
the absence of lateral slits in the former and their presence in the 
latter.” 
In the excellent and detailed description of the different organ . 
systems the following points are of especial importance: The pro- 
boscis has no retractor muscle, its posterior end lying entirely free 
in the rhynchoccel, exactly as has been described for Cerebratulus 
lacteus? The musculature of the proboscis consists of two principal 
layers arranged as in many of the Lineidz, and there are also more 
or less distinct muscular crosses so characteristic of this family. 
A strong layer of circular muscles surrounds the posterior end of 
the stomach, but ends abruptly at the beginning of the intestinal 
region. This forms a definite inner layer of circular muscles which 
the author looks upon as homologous with the inner circular layer of 
Carinella, and which is so highly developed in exactly the same 
region in Carinoma. Her views are well supported by diagrams 
and figures, and seem to be conclusive. A similar, but less highly 
developed, muscular layer has been described for Micrura. 
The cesophagus exhibits two well-marked regions differing greatly 
in histological features, the posterior cesophagal cavity, or stomach, 
being lined with cells which resemble far more closely those found 
in the intestine than those of the cesophagus proper. This suggests 
that the anterior cesophagal cavity only may have arisen from the 
ectoderm, while both stomach and intestine are derivatives of the 
entoderm. 
The caudal cirrus, or caudicle, has been studied in detail, and the 
statements of various observers who have described this organ erro- 
neously are corrected. The posterior opening of the intestine lies 
1 Coe. Trans. Connecticut Acad., vol. ix (1895), p. 488. 
