ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
619 
Mollusca. 
a. Cephalopoda. 
Anatomy of Nautilus Pompilius.* — Mr. J. Graham Kerr has an 
exceedingly interesting essay on the anatomy of this important Cephalo- 
pod. He has been so fortunate as to be able to examine 25 specimens, 
a number of which, however, were young and immature. Mr. Kerr 
finds that the perivisceral cavity is remarkable for consisting in almost 
equal parts of true coelom and haemocoel ; the latter is especially de- 
veloped in the headward section of the body. The coelom consists of 
two distinct chambers, genital and pericardial, separated by a perforated 
septum. Each of these chambers opens to the exterior by a pair of 
nephridia. Discussing the nature of the genital ducts, Mr. Kerr comes 
to the conclusion that in the Cephalopoda they represent portions of 
nephridia. The ovary was found to be remarkable for its extremely 
archaic character, that is to say, it has an ovigerous region of the coelomic 
epithelium roofed in by a simple up-growth of the coelomic wall. The 
ova were found to arise from syncytial masses of protoplasm. The testis 
also exhibits archaic characters, and is similar to the ovary in its main 
features. Its cavity, however, has become subdivided into numerous deli- 
cate tubes for the provision of a larger area of spermatogenic epithelium. 
Though the penis is said to be a paired structure, its left half is rudi- 
mentary. In contradiction to Prof. Ray Lankester, who says that no 
buccal nervous system has been observed in Nautilus , and that no enteric 
nervous system has been described, Mr. Kerr points out that a compli- 
cated buccal system was described and figured by Yon Ihering, while at 
least part of an enteric system was described by Keferstein. As Yon 
Ihering’s remarks are very brief, and in the construction of his diagram 
a serious blunder seems to have been made, which has been perpetuated 
by being copied by leading text-books, the author thinks it advisable to 
give a short account of the buccal nervous system. The result of this 
description, which is commendably short, is to show that an elaborate 
buccal system is present in Nautilus. For the structure which Lankester 
has called the inner inferior lobe, Owen stated that the innervation was 
effected by a small distinct ganglion on each side. Mr. Kerr, however, 
finds in his specimens that the lobe is innervated, not by a pair of 
distinct ganglia, but by a continuous nerve-cord. Around the post-anal 
papilla there is a curious system of skin-glands, which appears to have 
escaped the notice of earlier investigators. One of the most interesting 
of Mr. Kerr’s discoveries is a prolongation backwards of the nerve-trunk 
which supplies the gills. This probably represents the post-anal com- 
missure of Amphineura. The pedal nature of the Cephalopod arms is 
discussed in some detail, and reason is given for regarding the evidence 
on which it rests as being on insecure foundations. It seems desirable, 
indeed, to abandon it for the inherently much more probable view that 
these structures are processes of the head region, The relationships of 
Nautilus appear to be more with the Amphineura than with any other 
group of Mollusca, and amongst these the Chitons seem to be the oldest 
and most primitive. Mr. Kerr quite truly says that the number of really 
* Proe. Roy. Soc., 1895, pp. 664-86 (2 pis.). 
