140 Mr. W. J. Sollas on the 



to say. On the whole I am disposed to regard them as the 

 ordinary cells of the mark rendered very distinct by their oc- 

 currence in a tissue of markedly contrasted character. The 

 spicules which extend beyond the surface of the sponge might 

 perhaps suffice to convey a mechanical stimulus to the mus- 

 cular layer, though this view is certainly attended with serious 

 difficulties. 



2. Cortical Funnels or Chonce. — As the nomenclature ot 

 these organs is somewhat varied, one might almost say 

 " poikilitic," a short account of the various terms in use may 

 not prove superfluous. Most authors have founded their 

 terminology on their ideas of the homology of these organs 

 with the intermarginal cavities of Bowerbank; and while this 

 plan has its special merits it suffers from the serious draw- 

 back that ideas as to homology are liable to change with 

 advancing knowledge, the nomenclature must perforce change 

 with them, and changes in nomenclature are most undesirable. 

 Carter * abstains from committing himself and merely terms 

 these tubes the hourglass-shaped openings or hourglass 

 cavities. Bowerbank f and Oscar Schmidt J regard them as 

 corresponding to the intermarginal cavities of other sponges, 

 such as Chalina and Spongilla, though they do not say why 

 the " cortical funnels " and " subcortical crypts " should not 

 both together be regarded as representing the intermarginal 

 cavities. Hackel§ appears to share the views of Bowerbank 

 and Schmidt, but is anxious above all things to make it clear 

 that the intermarginal cavities are nothing more than modi- 

 fications of the ordinary "Astcanale," one of the bladders 

 of the " blasenformige " type of " Astcanal " which has be- 

 come specialized ; and he prefers to call them " subdermal 

 cavities," a term synonymous with Bowerbank's intermar- 

 ginal cavities. Perhaps I am wrong in thinking that the 

 homology of these cavities is not quite clear ; but, however 

 this may be, and without wishing " to ascribe any essential 

 significance to them whatsoever," I still think they are suf- 

 ficiently specialized parts of the canal-system and suffici- 

 ently different from other subdermal cavities to deserve a 

 distinct name ; and as " cortical funnel (chone) " is expressive 

 without involving theoretical considerations, I have ventured 

 to make use of it. Hackel compares the sphincters of the 

 funnels to the transitory sphincters which are formed by the 

 closing of the dermal pores and gastral ostia of some calca- 



* Carter, Ann. & Mag. Nat. Hist. 1869, ser. 4, vol. iv. p. 13. 

 t Bowerbank, Brit. Spong. vol. i. p. 101. 

 t 0. Schmidt, Adriat. Spong. ii. Suppl. p. 4. 

 § Hackel, Kalkschwamme, p. 236. 



