330 



Mr. H. E. Durham. Note on the [Jan. 26, 



phagocytes which pass out through the dermal branchiae. In 

 conclusion, I should state that clumps of corpuscles occur, here and 

 there, in the pore canals of the madreporite both of Asterias rubens 

 and Gribrella ocellata as seen in sections. The madreporites and 

 neighbouring structures were removed from full-grown specimens and 

 then placed in hardening fluids : this being so, I think it not impro- 

 bable that these corpuscles came from the cut end of the " heart," and 

 arrived at their position by the outward ciliary current, recently 

 described by Dr. Hartog.* It is difficult to conceive that such an 

 outflow of corpuscles should take place normally ; for then there 

 must be a continual loss of ordinary as well as of splicer ulijerous 

 corpuscles. 



EXPLANATION OF PLATE 3. 



FiQ-. 1. — Section through a dermal branchia of Asterias rubens, after Indian ink 

 injection, c. e., coelomic epithelium ; c. t., connective tissue; e, epidermis; 

 cut., cuticle. 



Fig-. 2. — Corpuscles containing granules of Indian ink, taken off a branchia. 



b, sphseruliferous corpuscle. 

 Fig. 3. — Section through terminal portion of dermal branchia. Note the plug of 



corpuscles (p) and crowding of epiderm nuclei at its sides. The other 



letters as in fig. 1. 

 Fig. 4. — Sphseruliferous cells from slime. I, liberated sphserules. 



J I. " Note on the Madreporite of Cribrella ocellata" By Herbert 

 E. Durham, B.A., lately Vintner Exhibitioner, King's 

 College, Cambridge. Communicated by P. Herbert Car- 

 penter, D.Sc., F.R.S., F.L.S. Received January 5, 1888. 



I have a series of vertical longitudinal (radial) sections carried 

 through the madreporite, &c., of a full-grown specimen of Gribrella 

 ocellata : in this series the madreporic canals have a peculiar relation 

 to the stone canal or water-tube. k 



Most of the pore canals pass into collecting canals which open into 

 the stone canal directly : some few, however, lead into the space 

 below the madreporite, which is the upper extremity of the 

 " schlauchformiger Kanal." The stone canal dilates laterally on 

 each side into an " ampulla" and one of these lateral lobes of the 

 ampulla has an aperture into the "schlauchformiger Kanal." Now 

 the " schlauchformiger Kanal " is derived from the enterocoele 

 (Hamann),f so that in the specimen described there is a permanent 

 connexion between the hydrocoele cavity and the enterocoele cavity. 



* M. M. Hartog, 'inn. Mag. Nat. Hist./ Nov. 1887. 

 t O. Hamann, ' Die Asteriden,' p. 51, Jena, 1885. 



