102 THE FAMII.Y OK THE DESMACIDINAE. 



Spongiologists follow the system of Schmidt. As a prin- 

 ciple at least,- for Schmidt himself has made several chan- 

 ges, Wyville Thom.son has made „slight modifications"'), 

 and Zittel proposed many very practical ameliorations. 



In the following pages I propose to describe and enu- 

 merate the species of Desmacidinae ; this family is taken 

 in the sense proposed by Schmidt in 1870 ^). Nevertheless 

 I have added the genus Clathria for reasons to be explai- 

 ned in due time. 



One word to explain the abreviations, which are made 

 use of in the descriptions of the species. In order to 

 facilitate the comparison of different species , I have long 

 since tried to indicate the spicules of the siliceous Sponges 

 by means of formulas or signs, which were based upon 

 the fundamental forms of the spicula, proposed by Schmidt ^) 

 viz. monaxial , tri-axial , tetraxial and polyaxial. 



The Desmacidinae only possess monaxial spicules: diffe- 

 rent kinds of smooth and spined rods *) and bows , and 

 bihamate spicules. These few forms are indicated by the 

 following signs: tr. (i^runcatus) == blunt, ac (aoutus) = 

 sharp, pointed. Thus tr. ac. means: blunt at one end. 

 pointed at the other. If the former is distinctly swollen , 

 an ° is put on the tr. , for instance tr°. ac If both 

 ends are blunt it must be tr. tr , or when at the same 

 time they are equal tr^. ; f(/usiformis) added to a sign 

 means : swollen in the middle; sp(spinosus) added to a sign 

 means : spined , thorny. Anc(«7?<'hora) = anchor. When 

 the number of the teeth can be distinguished the num- 

 ber of these can be added. 



And so we have : 



tr. ac. = acuate (= „Stifte" = „Stumpf-spitz.") 



1) Ann. ami. Mag. 1868 I p. 110. 



2) Grundziige einer Spongien Fauna cl(>s Ailaniisclien Gcbietes; jiag. 53. 



3) Ibid. p. 2. 



4) It is perhaps practical to designate by this word those spicules of which 

 the type is a simple rod (Stabnadel nf the nerm^ms, linear skeleton-spicula Crtr.). 



JVoles Iroiii the Ley*lcn IMiiseum, ^^ol. 11. 



