414 Dr. H. A. Nicholson on the Minute 



soaked in glycerine and water since its removal from the 

 intestine, it still assumes, when not prevented by pressure, 

 the same position by the elasticity of its body. If swallowed 

 alive it would most probably have died and have suf- 

 fered partial digestion before it had reached the lower part 

 of the ileum. Furthermore, the intestine of the worm is filled 

 with a reddish substance like the remains of blood ; and we 

 know that the Bats of the genus to which its host belongs 

 feed partially on the blood of smaller species of Bats ; so that, 

 even if the worm is not a true parasite, it is very probably a 

 messmate. 



I have much pleasure in connecting with the specific title 

 of this very interesting form the name of Dr. Macdonald, 

 whose valuable researches have so largely contributed to our 

 knowledge of the zoology of the Invertebrata. 



LIV. — On the Minute Structure of the Recent Heteropora 

 neozelanica, Busk, and on the Relations of the Genus Hete- 

 ropora to Monticulipora. By H. Alleyne NICHOLSON, 

 M.D., D.Sc, F.R.S.E. 



[Continued from p. 339.J 



Paet II. 



Having now considered the structure of the skeleton of a 

 recent species of Heteropora, we may pass on next to consider 

 the conformation of the corallum in Monticulipora, and may, 

 finally, come to some conclusion as to the extent to which the 

 two may be regarded as really similar to one another. That 

 there exists a general resemblance between the ramose or 

 dendroid forms of Monticulipora (using the term in its wide 

 sense) and the species of Heteropora is undeniable and has 

 long been known. Both consist, as regards their skeleton, 

 of fasciculate tubes, which are nearly vertical in the centre of 

 the branches, but which sooner or later bend outwards to 

 reach the surface, becoming thickened, or otherwise structurally 

 altered, in the latter part of their course. Nor is there any 

 difference in size, either as regards the skeleton as a whole or 

 the component tubes, which would prevent us comparing the 

 two ; while in both we have the remarkable feature that the 

 skeleton is composed (except in a few Monticuliporids) of 

 tubes which are not all alike, but which clearly differ, either in 

 size or in some other character, from one another. It becomes 

 therefore a matter of interest to discover how far this external 

 resemblance is accompanied by an agreement in internal struc- 

 ture ; and it is obvious that in investigating this point it is 



