376 Dr. E. von Lendenfeld on the Horny Sponges, 



lial as in the Hjdromedusfe. To enter into more detail upon 

 this subject, however, would lead us further than seems to be 

 permissible in a preliminary communication. 



]f I now glance back briefly over our knowledge of the 

 nervous and muscular tissues of the Sponges, it may, on the 

 one hand, be useful to my coUaborateurs in this department ; 

 while, on the other hand, such a summary may serve as a 

 foundation for general morphological investigations. 



In the first place, F. E. Schulze, the founder of modern 

 spongiology, demonstrated that in many sponges particular 

 fibre-cells, and even combinations of fibre-cells, are contractile. 

 This discovery thatthe long-known movements of adult sponges 

 (larva3, young Siwrigillcej &c. move without contractions of 

 fibre-cells) are caused, not by a contraction of the funda- 

 mental substance or of the epitheiia, but by contraction of 

 definite elements adapted to this purpose, has been repeatedly 

 confirmed by myself and others. 



In the year 1880 C. Stewart demonstrated " palpocils " in 

 Grantia compressa before a meeting of the English Royal 

 Microscopical Society. I am not in a position to offer any 

 opinion upon this statement, which only came to my know- 

 ledge a few months ago. I indeed regard the existence of 

 sense-hairs upon the sense-cells discovered by me as probable 

 upon a priori grounds, but I have never seen palpocils. 



I have investigated a number of Australian Calcispongise, 

 Myxospongise, and Horny Sponges, and have found upon 

 some, although only a few of them, cells which I regarded as 

 nervous. Among the Horny Sponges I have hitherto tested 

 in this respect only the Aulenina3 and the genus Euspongia 

 (the Australian species). The actual results in these groups 

 are as follows : — 



Sycandra arhorea^ Hackel. The sense-cells form a ring at 

 the entrance of the afferent canals. 



Grantessa sacca^ II. v. L. The sense-cells stand in groups 

 at the entrance to the afferent canals. 



Vosmceria gracilis, R. v. L., and Sgcandra pila, R. v, L. 

 The sense-cells stand in groups at a greater distance around 

 the incurrent apertures. 



Leucandra saccharata, Hackel, and Leucandra meandrina, 

 R. v. L. The sense-cells stand in groups which are scattered 

 irregularly over the surface. 



Leucetta microrhapkis and Leucaltis helena, R. v. L. The 

 sense-cells are scattered singly over the surface, but appear to 

 be more numerous in the vicinity of the incurrent orifices. 



Aulena villosa, R. v. L. The sense-cells are placed in 



