132 Dr. Strethill Wright's Observations on 



composed entirely of several (8-12) conjoined tubes (fig. 7) ; 

 reticulate by the lateral anastomosis of their tubes ; or consisting 

 of long ridges of tubes reared against each other. 



The polyps spring from one or several confluent tubes of the 

 polypary ; they are covered at their origin, and for a little di- 

 stance above it, by a delicate prolongation of the polypidom. 

 This may be detected by dyeing the whole zoophyte with tinc- 

 ture of kino, which gives different tints to its chitinous and 

 fleshy elements, or by steeping it alternately in spirit and water, 

 when the coverings of the polyps and polypary become inflated 

 as in figs. 2 & 3. 



The polyps are of several shapes and functions, which I have 

 described in the paper cited above. It will be sufficient to 

 enumerate them here : — 



1. Alimentary polyps, with mouth and tentacles. 



2. Reproductive polyps, with rudimentary mouth and tentacles. 



3. Spiral polyps— a modification of the last; generally barren 

 (fig. 3). 



4. Sessile generative sacs of the polypary. 



5. Tentacular polyps, or great tentacles of the polypary (fig. 2) . 

 In the reproductive organs of Hydractinia there is a gradual 



transition from the reproductive polyp to the sessile generative 

 sac; the polyp loses its dot-like mouth, its tentacles, its head 

 or upper part, and finally dwindles down to a mere sperm-sac. 

 This change is generally seen in those specimens which have 

 long been kept in captivity. In these specimens, too, many 

 of the alimentary polyps are often converted into large inflated 

 sacs destitute of mouth and tentacles, and showing through their 

 parietes white longitudinal ridges, which indicate the number of 

 zooid elements of which they are composed. 



In the natural history of this remarkable zoophyte there are 

 other points of peculiar interest, which, having already described, 

 I need only mention here :— the slow development and unique 

 shape of the planuloid larva ; the powerful muscular structure of 

 the polyps, especially the spiral ones, the office of which last has 

 yet to be discovered ; and the intimate sympathy and combined 

 action which subsist between the various parts of the whole 

 animal. 



Halcampa Fultoni, n. sp. (a parasitic Actinia). 



In a late volume (vi. p. 432) of this Journal appears an ac- 

 count of a parasitic Actinia, Philomedusa Vogtii, by Herr Fritz 

 M tiller. In 1858 I took a parasitic Actinia which evidently 

 belongs to the same genus. The following account of it is 

 extracted from the ' Proceedings of the Royal Physical Society,' 

 published in the ' Witness' on the 16th of May 1860. It was 



