148 Obituary Notices of Fellow* deceased. 



characteristic thoroughness. An interesting history is given of the 

 discovery by Peyssonnel of the animal nature of Corallium, and of 

 the incredulity with which Peyssonnel's results were received by 

 Reaumur and Bernard de Jussieu. 



The work on the Red Coral was succeeded by the memoirs on 

 Gerardia (1864), and other Antipatharia (1865). These papers 

 added not a little to the proper understanding of this group of 

 Zoantharia, and, in particular, they gave much needed information as 

 to the characters of the living polypes of the " Black Corals.'' 



Continuing his researches into the structure and development of 

 Actinozoa, Lacaze-Duthiers published, in 1872, his classical memoir 

 on the development of the Actiniaria. The account there given of 

 the order of the appearance of the mesenteries forms the basis of our 

 modern knowledge of this subject, and is well known to every 

 student of Sea Anemones. This memoir appears in the first volume 

 of the " Archives de Zoologie Experimentale et Generale," of which 

 the first number was ready for distribution in 1870, although the 

 outbreak of the Franco-Prussian War, in that year, delayed its 

 appearance until 1872. Lacaze-Duthiers' activity at this period is 

 strikingly shown by his own contributions to the first volume of the 

 "Archives." Besides the work on Actinians, the volume contains 

 a study by him of the otocysts of Molluscs, another on the structure 

 of aquatic Pulmonate Gasteropods, besides notes on the occurrence of 

 the stalked larva of Antedon at Roscoff, and on the remarkable 

 Chsetopods, Chtvtopterm and Myxicola, observed at the same place. 

 The treatise on the otocysts was summed up in the generalisation 

 that the " auditory " nerves of Mollusca always originate from the 

 supra-O3sophageal ganglia, in the neighbourhood of the optic nerves. 

 The supra-oesophageal ganglia are thus the centre which supplies the 

 principal sense-organs; while the pedal ganglia, with which the 

 nerves of the otocysts are often apparently connected, are purely 

 motor in function. There are, perhaps, few anatomical figures of 

 Invertebrates which have more frequently been copied than that of 

 Cydostoma elegans, which is published in this paper. The memoir 

 on aquatic Pulmonates, besides giving an elaborate account of many 

 other structural details, contains a description of a sense organ 

 which has often been referred to as " Lacaze's organ," and was 

 later identified by Spengel with the "olfactory organ" of other 

 Molluscs, a structure now usually known by Lankester's term 

 " osphradiurn." 



In the succeeding volume of the "Archives" (1873), Lacaze- 

 Duthiers reverts to the Actinozoa in a paper dealing with the anatomy 

 and development of Astroides calycularis. Here again he had the 

 good fortune to break fresh ground, and his paper was not only the 



