42 PROF. HUXLEY ON SOME POINTS IN THE 



of Valenciennes with regard to the existence of three pairs of 

 apertures ; but he showed, in opposition to him, that one of these 

 pairs of apertures communicated with the pericardium. The sacs 

 into which the other two pairs open are, according to this anato- 

 mist, blind. In the aperture of the anterior blind sac he found a 

 concretionary matter which he supposed to contain uric acid, but 

 chemical analysis did not confirm the supposition. Yan der Hoeven 

 refers to some observations by Yrolik ; but as these are in Dutch, 

 and have not, so far as I can find, been translated into either 

 French, German, or English, I know not what they may contain. 



In his more recent essay, translated in ' Wiegmann's Archiv ' for 

 1857, under the title of " Beitrag zur Anatomie von Nautilus 

 pom^iliuSj^^ Van der Hoeven states that he has again found hard 

 concretions in the chamber enclosing the appendage of the anterior 

 branchial artery, and that these on chemical analysis yielded phos- 

 phate of lime and traces of fat and albumen, but no uric acid. 



Mr. Macdonald, in a valuable paper on the anatomy of Nau- 

 tilus umhilicatus, published in the Philosophical Transactions for 

 1855, thus describes the follicular appendages of the branchial 

 arteries : — 



" These follicles are subcylindrical in form, somewhat dilated at 

 the free extremity, to which is appended a folded and funnel- 

 shaped process of membrane, which expands rather suddenly, pre- 

 senting a jagged and irregular border. They open by a smooth and 

 oval or slit-like, orifice into the afierent pulmonary vessels, on each 

 of which, as Professor Owen has observed, they are disposed in three 

 clusters. The outer membrane is smooth and glassy, homogeneous 

 in structure and sprinkled over with minute rounded and trans- 

 parent bodies, probably the nuclei of cells. Beneath this layer, 

 flat bundles of fibres, apparently muscular, are traceable here and 

 there, principally disposed in a longitudinal direction, and some- 

 times branched. The lining membrane consists of a loose epi- 

 thelial pavement in many respects similar to that of the uriniferous 

 tubules of the higher animals, the ceUs containing, besides the 

 nuclei, numerous minute oil-globules, or a substance much re- 

 sembling concrete fatty matter. This membrane is thrown up 

 into an infinite number of papillae and corrugations, so as to 

 augment the extent of surface considerably. The papillae are 

 more numerous at the inner part or towards the attached end; 

 and a circlet of longitudinally disposed folds radiate from the 

 bottom of the follicles, in which a number of small pits or fenestra- 

 tions are sometimes visible. Tlie sides of these folds are wrinkled 



