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PLUMATELLID^. 



Genus II. Pectinatella, Leidy, 1851. 



Name. — A diminutive noun, formed from pecten, a comb, in allusion to the form of its 

 tentacular crown. 



In the ' Proceedings of the Academy of Natural Sciences of Philadelphia ' for September, 

 1851, a new fresh-water Polyzoon is described by Dr. Joseph Leidy, under the name of 

 Cristatella magnifica. The statoblasts of this animal resemble those of Cristatella 7nucedo, 

 and it was this character which induced Leidy to refer his new Polyzoon to the genus Crista- 

 tella. It is not, however, furnished with a disc fitted for locomotion, and it has the orifices 

 scattered irregularly over the surface, characters which bring it very near to Lophojjus, but 

 which at once exclude it from the genus to which Leidy had referred it. Of the untenableness 

 of this association the author became almost immediately aware, and, in the next number of 

 the ' Proceedings,' he instituted for it a new genus, with the following diagnosis : 



Generic character. — " Coencecium massive, gelatinoid, hyaline, fixed, investing bodies ; 

 orifices arranged in irregular lobate areolae upon the free surface. Lophophore crescentic. 

 Ova (statoblasts) lenticular, with an annulus and marginal spines." Leidy. 



Species unica. Pectinatella magnifica, Leidy. 



Specific character. — Same as that of the genus. 



Synonyms. — 1851. Cristatella magnifica. Leidy, Proc. Acad. Nat. Sci. of Philadelphia, Sept., 

 1851. 

 1851. Pectinatella magnifica. Leidy, Proc. Acad. Nat. Sci. of Philadelphia, Nov., 

 1851. 



Iconography. — No published figure. 



Habitat. — "Ditches and sluggish streams; found only in shady situations; always 

 incrusting dead branches of trees." Leidy. 



Localities. — " About Philadelphia." Leidy. 



It is greatly to be regretted that we have no published figure of this beautiful Polyzoon, 

 which must well deserve the name by which the species is designated. Dr. Leidy gives us the 

 following more detailed description of it : 



" Polypidom massive, incrusting bodies, from a few inches to several feet in length, by a 

 few lines to two inches in diameter; gelatinoid, consistent, hyaline, with numerous polypi upon 



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