96 Z. HYDROIDA. Hydka. 



taenia in all my specimens have never exceeded the length of the 

 body, are usually seven or eight in number, and taper to the point 

 insensibly. Every part of the body is generative of young, which 

 may frequently be seen hanging from the parent at the same time in 

 different stages of their growth. Baker's figui'e represents this va- 

 riety very well. 



The second is a larger animal and comparatively rare, less sensible 

 to external impressions, and of a more gracile form. Its colour is a 

 dilute olive-green with paler tentacula, which are considerably long- 

 er than the body, and hang like silken threads in the water, waving 

 to and fro without assuming that regular circular disposition which 

 they commonly do in the H. viridis. I have not observed more 

 than one young at a time, pullulating from near the middle of the 

 body, and after this has attained a certain growth, the polype has the 

 appearance of being dichotomously divided. 



Dr Fleming's Hydra vulgaris, Brit. Anim. 553, embraces this 

 and the preceding, as well as the following species, which are consi- 

 dered the mere variations of one protean original ; — 



" Facies non omnibus una, 

 Nee di versa tamen :" — 



but the conviction of their permanent distinctness has been forced 

 upon me by a long continuous observation of individuals in a state of 

 confinement. Had, however, personal observation been wanting, the 

 same conclusion would have been willingly adopted on the paramount 

 authorities of Trembley and Baker, who had very carefully studied 

 these creatures ; and Pallas speaks very decidedly to the same pur- 

 port. " Species Hydrae a Linnaeo* pro varietatibus habitas, a Raese- 

 lio primum bene determinatas adoptavi, cum de trium priorum con- 

 stantia, propi'ia me experientia certissimum reddiderit." — Elench. 29. 



3. H. FUSCA, hrown or griseous ; inferior half of the body sud- 

 denly attenuated ; tentacida several times longer titan the body. 

 Vignette, No. 11, page 93. 

 Polypes a long bras, Tremh. Mem. pi. 1. fig. 3, 4, 6 ; pi. 2. fig. 1, 3, 4 ; pi. 

 3, fig. 11 ; pi. 5, fig. 1-4; pi. 6, fig. 3-7, 9, 10 ; pi. 8. fig. 8, 11 ; pi. 9. 

 copied in Adams, Micros. 399, pi. 21, fig. 7, 8 ; pi. 2-3, A. B ; pi. 24, A, 



B. fig. omnes. Cuv. Reg. Anim. ill. 295 Long armed fresh-water 



Polype, Ellis, Corall. xvi. pi. 28. fig. C. (the tentacula shortened for the 



conveniency of introducing them within the size of the plate.) Second 



sort of Polype, Baker, Polyp. 18. c. fig Hydra oligactis, Pall. Elench. 



29 H. fusca, Lin. Syst. 1320. Ellis and Soland. Zooph. 9. Berk. 



In the lOtli edit, of Syst. Nat. p. 810, under the name oi Hydra Polypus, 



