I'ORIFERA. II. 



respect the question is for the present only of the genera Myxilla—Lissodcudoryx and Desmacidon- 

 Homoeodictya; the particulars will be found under these genera. 



With regard to the examination I shall only add the further remarks that the examination of 

 the structure of the skeleton has generally been made on dried preparations placed in xylol in not 

 too thin sections, by which means distinct and complete views of the skeleton are obtained. Care 

 must be taken, of course, that the skeleton is not distorted by the drying. I mention this proceeding, 

 because I think it gives a better and more distinct view than is got when the sponge is cut in a 

 moist state, and by the use of my descriptions of the skeletal structure it must be remembered that 

 they are made from such preparations. For the examination of the structure of the spicules I have 

 generally used Canada balsam-preparations; in a few cases I used Naphtalin-a-monobromatum, which 

 proved to be very good when the question was of very thin silicious plates; also a mixture of Naph- 

 talin-a-monobromatum with Canada balsam was in some cases found to be good. Storax resolved in 

 benzol and alcohol has been used in a few cases; but in by far most cases Canada balsam proved 

 very efficient; when the spicules are completely cleaned, it will in balsam-preparations almost always 

 be possible to study the structure to the finest details. 



Fam. III. Desmacidonidae. 



Subfam. i. Mycalinae. 



Group, i. Mycaleae. 



According to what has been shown by Thiele (Abhandl. der Senckenberg. nat. Gesellsch. XXV, 

 949) the name of Esperella Vosm. must be altered to Mycale Gray, and consequently the name of the 

 subfamily and the group will also have to be altered. 



Esperiopsis Carter. 



The form varying ; in crusting or irregularly solid, but frequently erect and Icuf-shaped, or in 

 other xvays symmetrical. The skeleton may be constructed in various ways; in the erect forms it may 

 consist of long, well developed and branched fibres, but in the solid forms and in the iuerustiug ones it 

 rets a halichondroid or renicrid structure. Spongin is most frequently present . the amount varying. Spi- 

 cula '■: Megasclera monactinal, styli or subtylostyli; microsclera; the characteristic microsclera are isochelce 

 palmatce, which may occtir in one or several forms ; to these may be added isochelce arena fee, sigmata of 

 one or more forms, foxa, or forcipes in different combinations. 



The genus Esperiopsis was establised by Carter in 1882 (Ann. Mag. Nat. Hist. 5, IX, 296) for 

 the species villosa, which he had originally referred to Espcria. The distinctive character of the genus 

 is the fact that the characteristic microsclera are isochelse, which was also the principal reason why 

 Carter separated the species into a particular genus; to be sure he mentions also some other features, 

 but they are of no consequence. Levinseu (Studier over Svampe-Spicula: Cheler og Ankere; Vidensk. 



.s 



