214 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the vesicle rapidly disappears. There is no relation whatever between 

 these constituents of the follicle and the larval test, either as to the 

 time of their appearance, or as to their histological constitution. The 

 granular corpuscles and the gelatinous layer have no relation to the 

 mantle of the adult Tunicata, but form a provisional or larval organ 

 of protection, which in the genus Doliolum takes on a fusiform shape, 

 which is at first soft and applied to the body of the larva, but, later 

 on, becomes rigid, and swells out so that it is separated by the 

 gelatinous layer from the contained larva. 



The author postpones for the present a consideration of the views 

 of Sabatier, who, as the readers of this Journal know, has been a great 

 deal occupied with the same subject. 



Simple Ascidians of the Bay of Naples.* — P. A. Traustedt gives 

 a list of the species of simple Ascidians found in the Bay of Naples : 

 in addition to the bibliography and description of the species and 

 genera, there is a classification of the four genera of the PhallusiidsB 

 and of the Cynthiidaa. The new forms described are the Phallusia 

 quadrata, ohlonga, malaca, pusilla, and ingeria ; and Polycarpa mayeri, 



Urnatella gracilis, a Fresh-water Polyzoan.t — A paper on this 

 polyzoan, by Professor J. Leidy, has been recently published. It was 

 originally discovered in 1851, and briefly noticed in the same year, 

 and also in 1854, 1858, and 1870. It was found in the Schuylkill 

 Eiver at Philadelphia, but has not been seen elsewhere, except a dried 

 specimen on the shell of a Unio from Ohio. 



Urnatella is a most beautiful form, living in association with 

 Plumatella and Paludicella, and having similar habits, but is very 

 different from them or any other known fresh-water polyzoan. It 

 is most nearly related to the marine genus PedicelUna. It is found 

 attached to the under side of stones beneath which the w^ater can flow. 

 As commonly observed, it consists of a pair of stems divergent in 

 straight lines, or rather gentle curves, from a common disk of attach- 

 ment. The stems slightly taper, and are beaded in appearance, due 

 to division into segments alternately expanded and contracted. The 

 segments commonly range from two to a dozen, proportioned to the 

 length of the stem, which, when longest, is about the eighth of an 

 inch or a little more. The stems terminate in a bell-shaped polyp, 

 with an expanded oval or nearly circular mouth slanting to one side, 

 and furnished with about sixteen ciliated tentacles. The stems also 

 usually give off a pair of lateral branches from the second segment 

 succeeding the polyp, and frequently likewise from the first segment. 

 The branches consist of a single segment or pedicle supporting a polyp, 

 and usually give off similar secondary branches. The first and second 

 segments are cylindroid, highly flexible, and mostly striated and 

 colourless, and appear mainly muscular in structure. The succeeding 

 segments are urn-shaped ; the body of the urn being commonly pale 

 brown, ringed with lines, and marked with dots of darker brown. 



* MT. Zool. Stat. Neapel, iv. (1883) pp. 448-88 (5 pis.), 

 t Sep. Eepr. Journ. Acad. Nat. Sci. Philad., ix. (1883) 16 pp. (6 figs, and 

 1 pi.). Cf. Science, ii. (1883) pp. 789-90 (2 figs.). 



