Mr. W. L. Distant on the Genus Terias. 377 



small groups at the lines of union of the membranes, which are 

 extended in the vestibular space. 



Halme glohosa, R. v. L. The sense-cells stand in groups 

 at the edges of the membrane which are extended in the 

 lacunar spaces of the afferent canal-sjsteni. 



Euspongia canaliculata^ R. v. L. The sense-cells form 

 zones which surround at the surface the lacunar dilatation of 

 the efferent canal-system. 



These isolated observations do not enable us to draw any- 

 general conclusion, as the observations on the various species 

 are so very different. 



I have already indicated * that Schulze's denomination of 

 the contractile elements as " contractile fibre-cells " is no 

 longer necessary, and may now be replaced by the designation 

 " muscle-cells," seeing that nervous elements have been 

 found with them. 



Both the muscle- and nerve-cells are mesodermal. The 

 epithelia of the Sponges nowhere appear to be further deve- 

 loped after the fashion of the higher Coelenterata. Both 

 endoderm and ectoderm always remain simple f. 



XXXIII. — A few Remarks on Mr. Butler'' s Notes on the Genus 

 Terias. By W. L. Distant. 



In the last number of this Magazine I have read with no 

 inconsiderable interest a paper by my friend Mr. Butler, entitled 

 " Notes on the Genus Terias^ In this communication tlje 

 author, after expressing the very sound opinion that " it is quite 

 impossible for any one, in our present profound ignorance of 

 the earlier stages of most of the species and our imperfect 

 knowledge of those of all, to lay down the law as to which 

 of these forms is worthy of a distinctive name and which not," 

 has still been compelled to describe twelve new species, and 

 also to again do me the kindness of not only reviewing some 

 of my recent work, but also to contribute much readable criti- 

 cism thereon, and to offer many alternative suggestions for my 

 consideration. Under these circumstances I have felt it 

 would be discourteous to any longer refrain from affording 

 Buch explanation as is possible to one who has taken the 

 trouble to read my remarks, and also I have considered it 

 necessary to myself to show that the views I had the temerity 



* Zoologischer Anzeigei", no. 186. 



t Iliickel has described some Calcisponges Avith locally plurilamellar 

 endoderm, but hitherto this statement has not been confirmed. See also 

 Vosraaer in Bronn's * Klassen und Ordnungen desThierreiches : Porifera.' 



