118 



ANTHOZOA HYDROIDA. 



magnified figure represents the polypidom as unjointed or con- 

 tinuous, whereas it is regularly jointed both in the Campanularia 

 and Piumularia. But I make this remark, not to invalidate the 

 opinions either of Dr. Fleming or Mr. Hogg, for that of the former 

 I am disposed to adopt ; but it gives me an opportunity of warning 

 the student against an implicit reliance on the figures of Lamou- 

 roux, which we are assured by Blainville, who has compared them 

 with the specimens from which they were made, are in many in- 

 stances very erroneous. 



Fig. 24. 



Since the preceding sheet was printed, I have received from my friend, the Rev. 

 D. Landsborough, a specimen of PLUMULARIA MYRIOPHVLLUM with ovaries. 

 These are very peculiar, and unlike any I have observed in any other Sertularian 

 zoophyte. In the ovigerous pinnules there arises from the base of the polype-cell, 

 and on its outer side, a long gracefully curved process ; and as all the processes 

 curve round in one direction, they give the 

 pinnule a secund character and habit very 

 different from that of the barren shoots. The 

 processes are alternate, hollow, coarsely denti- 

 culated on the external edge ; and at their 

 base, opposite the polype-cell, the ovaries are 

 situated. These are didymous or in pairs, 

 sessile, smooth, resembling a mussel-shell in 

 shape, and easily detached. They differ from 

 the horny vesicles of the Sertularinae in 

 texture and in shape, and may best be de- 

 scribed as naked ovaries. The spinous process 

 which protects them appears to be formed by 

 a prolongation of the spine that supports the 

 barren polype-cell. (Fig. 24.) 



In a very ingenious essay on the morpho- 

 logy of the reproductive system of the Ser- 

 tularian zoophyte, Professor Edw. Forbes has 

 remarked that a dismemberment of the genera 

 Sertularia and Piumularia will follow from his 

 deductions relative to the composition of the 

 ovarian vesicle. (Ann. and Mag. N. Hist, 

 xiv. p. 390.) The latter genus is eminently 



artificial. 1. Piumularia falcata has a peculiar habit and a simple vesicle. 2. Piu- 

 mularia cristata, and pennatula, agree in their dense horny structure and podded 

 vesicles ; and to them PI. myriophyllum must be united, for its spinous processes 

 are really the crested bands of the vesicles of the other species in a free or detached 

 form. 3. Piumularia pinnata, setacea, and Catharina seem to be more nearly related 

 to the Campanulariadae, of which family their embryology may vet prove them to 

 be members ; and, notwithstanding its robust habit, PI. frutescens may be equally 

 referable to this category. 



