RECENT ADVANCES IN SCIENCE 417 



and Australian Homoptera," by Distant (ibid.) ; " On the 

 Occurrence of a Pseudoparasitic Mite (Cheletiella parasitivorax , 

 Meguin) on the Domestic Cat," by Hirst (ibid. July 17) ; " Re- 

 marks on Certain Species of the Genus Demodex Owen (the 

 Demodex of Man, the Horse, Dog, Rat and Mouse)," also by 

 Hirst (ibid. September 17). 



An account of certain " Experiments and Observations on 

 Crustacea. Part IV. Some Structural Features Pertaining to 

 Glyptonotus," by J. Tait (Proc. Roy. Soc. Edin. vol. xxxvii. 

 July 1 7). The large size of this Isopod renders it a very suitable 

 object for elucidating certain points in its functional anatomy 

 that are not readily determinable in smaller species. It is 

 suggested that the median split in the thoracic segments is to 

 allow of a distension of the body. The cephalosome, consisting 

 of the head and two thoracic somites, contains a well-developed 

 endophragmal skeleton which constitutes a strong maxillo- 

 sternal framework capable of independent movement. Glypto- 

 notus is carnivorous, and the fore-gut is not provided with a 

 gastric mill, but involutions of its wall aid in the swallowing of 

 food. The same author has also provided " Experiments and 

 Observations on Crustacea, Part V., a Functional Interpretation 

 of Certain Structural Features in the Pleon of Macrurous 

 Decapods " (ibid.). 



Other papers include : " The Malacostraca of Durban 

 Bay," by Stebbing (Ann. of the Durban Mus. vol. i. July 17). 



Vertebrata. — "The Homologies of the Muscles related to the 

 Visceral Arches of the Gnathostome Fishes," are discussed at 

 length in a well-illustrated paper by Allis (Quart. Jour. Micro. 

 Sci. vol. lxii. August 17). It appears probable that primitively 

 the muscles of the visceral arches in Gnathostome Fishes were 

 represented by a simple constrictor muscle in each arch, which 

 had associated with it a branchial bar lying on its internal side. 

 Two distinct lines of differentiation lead from this condition, 

 one represented by the Teleostomi and the other by the Plagio- 

 stomi, while the Holocephali and Dipneusti are apparently 

 intermediate between them to some extent. The four typical 

 elements of the bar in Teleostomi are arranged in practically a 

 single plane. In the Plagiostomi, however, we find the dorsal 

 and ventral elements directed postero-mesially at a marked 

 angle to the middle and so forming a sigma-shaped bar. In 



