FEB 



1893 



1^0. 1. — On Urnatclla gracilis. By C. B. Davenport.^ 



Contents. 



I. Introduction 



II. Anatomy 



1. Tlie Stalk 



2. The Calyx 



III. Non-sexual Reproduction . . 



1. Architecture of the Stock . 



2. Segmentation of the Stalk . 



3. Orientation of the Individ- 



uals 



Page 

 1 

 3 

 3 

 9 



16 

 16 

 19 



22 



Pacb 



4. Histology of the Buds . , 24 



5. Formation of new Stocks . 24 



6. Formation of the Individual 28 



7. Regeneration 29 



IV. Affinities of Urnatella ... 30 



V. Affinities of the Bryozoa . . 30 



VI. Summary 35 



VII. Literature cited 36 



Analytical Index 38 



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 coenoecium 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 *' coenoecium," 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 : " Coenoecium 

 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 Zoological Laboratory of the Museum of Comparative 

 Zoology, under the direction of E. L. Mark, No. XXXIII. 

 VOL. XXIV. — NO. 1. 1 



