No. 1. — On Urnatella gracilis. By C. B. DAVENPORT.! 
CONTENTS. 
PAGE PAGE 
E Introdubtlon «610v. 1 4. Histology of the Buds . . 24 
Ts sAMBtOMY Po en a 8 5. Formation of new Stocks . 24 
LG SIE 6 ne m é 6. Formation of the Individual 28 
AID, OBS WAS UE yo 9 7. Regeneration . . . . . 2 
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 ...... . 35 
3. Orientation of the Individ- VIL, Literature cited... vo ees 00 
Wg) O Dis ES ADE ya Inter c v as US 
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 conweium 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 “comacium,” 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: “ Joenoecium 
consisting of a series of segments up to eighteen in number, and forming 
free, semi-crect, 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 Zoölogical Laboratory of the Museum of Comparative 
Zoölogy, under the direction of E. L, Mark, No. XXXIII. 
VOL. XXIV. — NO. 1. 1 
