6(X Miscellaneous, 



as they descend to the centre of the lobe, they diverge more and 

 more, and cross each other to form a plexus, first with oval and 

 then with broader meshes, in which the nuclei and nucleated cells 

 are collected into groups of corresponding shape and size. 



From the plexus at the inner side of the lobe bundles converge 

 from all parts to form the lower half of the peduncle, the upper 

 part of which consists of masses of small nuclei, and gives attach- 

 ment, by a short pedicle, to a small tubercle. This tubercle consists 

 of closely aggregated nuclei connected by fibres which converge to its 

 neck and escape into the peduncle of the optic lobe. 



xlfter concluding his description of the optic lobes, the author 

 gives a short account of the structure and connexions of the remain- 

 ing cerebral ganglia of the Cuttle-fish, with the view of determining 

 their homologies. 



From the nature of the parts which it supplies, the foremost or 

 pharyngeal ganglion would seem to combine the function of the 

 centres which give origin to the trigeminal, the olfactory, and the 

 gustatory nerves in the vertebrata. The second bilobed ganglion 

 appears to correspond partly to the cerebral lobes and partly to the 

 cerebellum of fishes. The posterior portion of the subcesophageal 

 mass is the analogue of the medulla oblongata ; while the anterior 

 portion may be regarded as the spinal cord concentrated below the 

 oesophagus and in the neighbourhood of the feet, which derive all 

 their nerves from that source. 



MISCELLANEOUS. 



The ''Monde de la Mer.'* 

 [To Br. J. E. Gray, F.R.S. ^c] 



My dear Sir, — I* have just returned from a visit to the "Monde 

 de la Mer," a noble aquarium opened to the public, at a charge of 

 two francs per head, within the last week, on the Boulevard Mont- 

 martre. It is arranged as a large grotto, with cement stalactites, 

 and the light almost entirely comes through the glass front of the 

 aquaria. 



There are no less than thirteen aquaria, with glass fronts, about 

 15 feet long, 4 feet deep ; and there are glass facings to brick-and- 

 cement tanks 5 or 6 feet wide. These thirteen are for salt water 

 alone ; but there are others for fresh water, and two little ponds, 

 10 or 12 feet across. The aquaria are lit by gaslights placed above, 

 which light up in the most efficient manner the interior, and show 

 every fish most perfectly. 



There appears to be no confervoid growth ; and doubtless the 

 gaslight is unfavourable to such vegetation, but gives an illumina- 

 tion more resembling the natural condition in deep water. 



A gas-engine is employed to change the water, which continually 

 funs to a tank below, and is |pumped back, the jet being thrown 



