Mr. H. J. Carter on Parasites of the Spongida. 161 



firm to support several patches of a parasitic polyp, to me 

 identical with the PalytJioa fatua of the glass cord in Hyalo- 

 nema Sieholdu &c. 



On the other hand they are present at such an early period 

 in some sponges that at first it seems as if they were part of 

 the sponge itself, or, at least, developed in combination with it. 

 But when we reflect on the unerring certainty with which the 

 pollen-grains of dioecious plants find their way to the stigma 

 of the female flower through the air^ and, indeed, the sperma- 

 tozoa of the myriads of beings, both animal and vegetable, 

 growing together on our shores, tiud their respective species 

 amidst hosts of otliers on the same errand, through the sea^ 

 we cannot wonder that a similar instinct directs the parasitic 

 Zoanthidss in their embryonic state to find the objects on 

 which they respectively prefer to dwell. At the same time, as 

 these polyps are not seen on the sponge at a very early stage of 

 development, nor are always present on the same species, it 

 is evident that they are not a part of the sponge, nor ^^vo,- 

 loped pari passu with it; while it is equally evident that, in 

 the Jirst instance, they must have come from an unparasitic 

 Palgthoa, and therefore have obtained their specific differ- 

 ences subsequently, although, when once these have been ob- 

 tained, they continue, from adaptation, to prefer their new 

 habitat to that of the original stock. This, indeed, is the law 

 of adaptation and inheritance. 



Hydeozoa oe Hydeoid Polyps. 



While in all cases of Actinozoic parasitism that have come 

 to my notice in sponges the polyps have been confined to the 

 surface, those of Hydrozoic parasitism have extended into the 

 deepest jjctrts of the sponge, and, in one instance, have been 

 entirely confined to the interior. 



Taking, first, those whose tubes opened on the surface — 

 one was found by Dr. Allman in a " horny sponge on the 

 southern shores of France " and called by its discoverer 

 '^ Stephanoscgjyhus mirahilis " (Trans. Linn. Soc. 1875, ser. 2, 

 vol. i. pt. i. tab. xiv. ; and ' Nature,' 1874, July 80, p. 251) ; 

 and the other in Beniera fihidata, Sdt., Suherites flavus, 

 Liebkh., Esperia Bauriana, Sdt., and Myxilla fascicularis, 

 Liebkh., respectively, by Prof. F. E. Schulze in the Adriatic 

 Sea, who designated it Spongicola fistularis (Archiv f. 

 mikroskop. Anat. 1877, Bd. xiii. p. 795, Taf. 45-47) ; while 

 the instance in which the Hydrozoon was confined to the 

 interior of the sponge occurred to myself, and was noticed in 

 a specimen of Beniera [B. polypifera, Cart. MS.) from Bona 



Ann. & Mag. N. Hist. Ser. 5. Vol. ii. 11 



