No. 1.— On Urnatella gracilis. By C. B. DAvVENPorRT.! 
ConTENTS. 
PAGE PAGE 
I. Introduction Eh ace ie 1 4, Histology of the Buds . . | 24 
IAP ATIAtOMyss vA w it FP) i vey ay. ¢ 3 5. Formation of new Stocks . 24 
1. The Stalk fs: Aes al hac 3 6. Formationofthe Individual 28 
emer Cal y x-gespitmy. Me = es 9 ie Regenerations ys) sae 4 20 
III. Non-sexual Reproduction . . 16} IV. Affinities of Urnatella . . . 30 
1. Architecture of the Stock . 16| V. Affinities of the Bryozoa . . 30 
2. Segmentation of the Stalk . 19] VI. Summary ....... 385 
3. Orientation of the Individ- Villlniterature cited ha: irnes s\-ton- eae 
ThE esac teeta on eee fe 22| Analytical Tndexys Gan teh ee eee ae 
I. INTRODUCTION. 
In November, 1851, the late Dr. Leidy published, in the Proceedings 
of the Academy of Natural Sciences of Philadelphia, a notice of ‘ what 
I suspect to be the ccenecium of a new genus of Polyzoa; although I 
have never been able to detect the polypides if such exist.” He gives 
three figures of the “ccencecium,” consisting of a series of urn-shaped 
segments placed so that the base of one segment rests on the mouth of 
its proximal neighbor. To this new genus he gives the name Urna- 
tella, with a genus diagnosis, which three years later (’54, p. 191), after 
discovery of the polypide, was revised to read as follows: ‘“ Coencecium 
consisting of a series of segments up to eighteen in number, and forming 
free, semi-erect, curved stems, attached only by the base of the lowest 
segment. Segments excepting the three last ones simple, urniform ; the 
antepenultimate and the penultimate oblong, with simple or compound 
branches of the same form ; the last segment or active polyp is campanu- 
late, and is supplied with cylindrical, ciliated arms arranged in a circle 
around the mouth.” He finds that several stems arise from a common 
base. There are fourteen tentacles. 
In 1856 Allman (pp. 117-119) referred to the discovery of Leidy, and 
published a pencil sketch of Urnatella furnished by Leidy. This is ‘the 
1 Contributions from the Zodlogical Laboratory of the Museum of Comparative 
Zovlogy, under the direction of E. L. Mark, No. XXXIII. 
VOL. XXIV. — No. 1. 1 
