117 



URNATELLID^. 



Genus YU. Urnatella, Leid^, 1851. 



N'ame. — A diminutive noun, formed from urna, an urn, in allusion to tlie urn-shaped fip^ure 

 of the articulations. 



We find, in the fifth volume of the ' Proceedings of the Academy of Natural Sciences of 

 Philadelphia,' a new Polyzoon described by Dr. Leidy under the name of Urnatella (/mcilis. 

 It resembles, as Dr. Leidy informs us, a miniature Isis hippiiris, and was discovered growing 

 upon the under side of stones, in the River Schuylkill, near Philadelphia. Dr. Leidy accom- 

 panies his communication with a figure of the coenoecium ; and though he had not succeeded 

 in detecting the polypides, he felt himself justified in viewing the production in question as a 

 true Polyzoon. 



At a subsequent meeting of the Academy (' Proc. Acad. Nat. Sc. of Philadelphia,' 

 vol. vii. p. 191), Dr. Leidy again offers some remarks on Urnatella gracilis. Since his previous 

 communication, he had detected the polypides, and had also in other respects succeeded in 

 making a more satisfactory examination of the new Polyzoon, so that he now finds it neces- 

 sary to alter in some points his previous description. 



His account is confined to a generic and specific diagnosis, from which it appears that 

 Urnatella t/racilis is a most remarkable animal, and one of the most beautiful of the fresh- 

 water Polyzoa. The following are the characters given by Leidy in his amended diagnosis : 



Generic character. — " 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 campanulate, and is supplied with cylindrical ciliated arms, arranged 

 in a circle round the mouth." Leidy. 



Species unica. Urnatella gracilis, Leidy. 



Specific character. — •" Stems single or in groups up to six in number, attached at the 

 loM^er extremity by means of a sienna-coloured granular substance. Urniform segments 

 225 mm. long by "18 mm. broad, becoming smaller towards the free end of the stems; 

 body portion of each urniform segment translucent, whitish, with sienna-coloured 

 transverse striae and puncta;, and having on each side near tlie bottom a roundish process, 

 the remains of former branches ; the narrow top and bottom portion of the segments brown 

 in colour and annulated. The antepenultimate and penultimate segments and their branches 

 oblong, translucent. Polyp. '225 to ■4.5 mm. long, campanulate ; expanded, mouth circular. 



