790 ' REPORT— 1900. 



of old age. A well-developed tentacle of Mnestra is a compound tentacle of 

 undoubted Cladonemid type. The base is swollen and simple, but the distal 

 portion is slfudtr and tapering-, with a row of small stalked multinucleate club- 

 shaped bodies along the entire length of one margin. These bodies contain 

 nematocysts, and they are undoubtedly homologous with the stalked clubs 

 containing thread cells of many of the Cladonemid genera. 



A further poiut of resemblance between Mnestra jmrasites and certain of the 

 Cladonemidse is in the fact that there is a circular tract of nematocysts arranged 

 round the umbrella margin, close to the circular canal, and from this circular 

 tract extend four centripetal tracts along the perradii of the ex-umbrella. These 

 perradial tracts usually extend as far as the exumbral ' dimple ' and sometimes 

 continue down into it. 



The gastro-vascular system is of the usual type. There are a central stomach, 

 four radial canals, and a circular canal. The stomach is of an irregular shape and 

 is orten provided with irregular diverticula in which corpuscles which originally 

 belonged to the blood of the Phyllirhoe may sometimes be seen. The mouth is 

 clogged with endoderm cells with intercellular spaces through which the organism 

 imbibes its nutriment. 



Among the 100 odd individuals examined a number of varieties and abnormal 

 forms were observed. A description of these ao well as the histology of Mnestra 

 will shortly be published in the Naples ' Mittheilungen.' 



2. TJie Respiration of Aquatic Insects. By Professor L. C. Miall, F.E.S. 



3. The Tracheal System o/Simulium : a Problem in Resjnration. 



By T. H. Taylor. 



4. The Pharynx of Eristalis. By J. J. Wilkinson. 



The Structure and Life History of the Gooseberry Saufly. 

 By N. Walker. 



6. Report on the Coral Reefs of the Indian Region. — See Eeports, p. 400. 



7. Contributions to the Anatomy and Systematic Position of the 

 Loimargidce. By Professor E. Burckhardt. 



8. On the Nestling o/" Ehinochetus. By Professor E. Burckhardt. 



9. The Dentition of the Seal. By E. J. Anderson, M.A., M.D., 

 Professor of Natural History, Gahvay. 



The dentition of the common seal is generally understood to be in the great majo- 

 rity of cases f I., ^ C, ^ P.-m., ^ M. There may be an additional premolar, due to 

 the persistence of one of the milk-teeth. The molars are not too much crowded 

 in the upper jaw, but more so in the lower. The incisors have standing room, but 

 the central of the lower jaw show a disposition to stand back ; the small platform 

 on which the latter seem to stand narrows anteriorly, and the sockets are deeply 

 sunk in front of tjiis pique. The four inpigors of the Jower jaw correspond to the 



