106 B. W. PRIEST ON THE CALCAREA. 



comprised in the two orders HomocceJa and Heteroccela. The 

 throe firsl mentioned being frequently met with on our own shores, 

 and often found growing together, will give anyone interested in 

 the subject plenty of opportunities for studying their histology. 



In preserving and mounting in the dry state the Calcarea, or 

 portions of the same, small specimens can be selected and mounted 

 in Canada Balsam in glass colls, fixed to the slip with marine glue, 

 and also vortical sections done in the same way. To preserve the 

 spicules of the different species apart from the sponge, heat por- 

 tions in liquor potassae, when they will soon separate and fall to 

 the bottom of the vessel, washing well with distilled water and 

 mounting in Canada Balsam. Do not attempt to mount in gly- 

 cerine, as, being calcareous, they will be sure in time to dissolve 

 away. 



For examining the soft structures of these sponges, put them 

 straight from the sea-water into a one-per-cent. solution of osmic 

 acid, when, on cutting sections tolerably thin, the collared cells, 

 with their flagellar expanded, will remain intact, and other struc- 

 tures, which would otherwise be shrivelled up and lost, can be 

 tolerably well made out with high powers. 



To those who would wish to go further into the histology of the 

 subject, I would recommend them to consult Haeckel's " Mono- 

 graph of the Calcareous Sponges," Dr. Bowerbank's monograph of 

 the same, and Dr. Polejaeff's " Report on the Calcarea of the 

 Challenger Expedition/' to which may be added .Air. Carter's 

 account of the same from South Australia in the " Annals of 

 Natural History" for 1886. 



The following is a list of Calcareous Sponges found on the 

 British Coast : — 



fj'ucosohnia botrt/oides (Bk.). 



Leacosolenia contorta (Bk.). 



/. ucosolenia coriacea (Bk.). 



Leucosolenia laciinosti (Bk.). 



/. ucosolenia lacunosa, var. Hillierii (Carter). 



Ascaltis Darwinii (Haeckel). 



Clathrina clathrus (Gray). 



Gran ti> compre8sa (Fleming)! 



Qrantia cili<it>i (Fleming). 



Grantin t uxcita (Bk.). 



Grantia tessi llata (Bk.). 



