LOXOSOMA. 373 



Pedicellina, on the contrary, are strongly built ; their movements 

 are energetic, abrupt, and even violent, as compared with the 

 slow and languid undulations of the Loxosoma, a fact which is 

 explained by the difference in the muscular fibres of the two. 

 The cuticle of the former is much thicker and stouter, the hypo- 

 derm more highly developed, all the organs are more distinctly 

 defined, and there is much less transparency than in Loxosoma. 

 The same differences are observable in the embryos of the two 

 forms. 



A very close relationship between the two genera must be 

 admitted, notwithstanding these differences and others which 

 might be mentioned in the buds and embryos. With respect to 

 the former, though differently placed in the two genera (on the 

 body of the polypide in one and on the stolon in the other), it is 

 probable that the course of development is the same in both. 



The difference in the gemmation, which corresponds, no doubt, 

 with the mode of attachment, may be regarded as an adaptation 

 fitting the Loxosomas for their semi-parasitic life; but the 

 Author remarks that the fact is not explained by the mere use of 

 the word " adaptation.^' The Pedicellinae attach themselves to 

 plants and various submarine bodies by stolons, on which the 

 gemma, are developed. The Loxosomas are solitary animals, and 

 adhere by the foot or base of the body, while the buds originate 

 from the. skin of the body. But if in the case of those species 

 of Loxosoma, which attach themselves to annelids, &c., with a 

 contractile skin, the habitat accounts for the absence of a stolon, 

 which would be continually broken by the contractions of the 

 animal, it is otherwise with those that are found on the stationary 

 Bryozoa, whose polyzoaries offer a more rigid surface than that of 

 the sea-weeds infested by the Pedicellince. 



The Loxosomas are said to pullulate on the glass of aquaria 

 in Naples. If they are adapted to a semi-parasitic life, how 

 comes it that they abandon this life by fixing themselves in the 

 same way as upon the animal on a smooth and lifeless body ? 



In the embryo of the two genera, the Author recognises simi- 

 larity of general plan combined with profound differences in 

 detail. The more matured condition, so to speak, of the 

 Pedicellina embryo has been referred to. Other points of dif- 

 ference may be found in the more perfect development of the 

 intestine in the latter, the presence of rudimentary generative 

 organs, eye-specks, and perhaps of the central nervous system, 

 which is entirely wanting, it would seem, even in the" adult 

 Loxosoma, and in the absence of the spectacle-organ, which is 

 replaced by two highly contractile lateral processes, ciliated at 

 the extremity. 



The Author does not share the doubts that have been ex- 



