1872.] DR. J. S. BOAVERBANK ON THE SPONGIADjE. 62" 



ternal defensive spieula: primary series large and long acerate spi- 

 cula, usually obsolete ; secondary series aceTate, minute. Oscula 

 simple, small, and numerous, usually congregated in deep cavities. 

 Pores congregated in minute areas ; porous areas conspicuous, very 

 numerous. Dermal crust rather thin, composed of small globose 

 ovaria. Dermal membrane thin and pellucid, abounding with minute 

 cylindro-stellate spieula, rarely subsphero-stellate ; radii numerous. 

 Skeleton — spieula fusiformi-acerate, rarely acuate, large and long ; 

 connecting spieula patento-ternate, stout, terminations of the radii 

 occasionally recurved ; and also with numerous slender recurvo- 

 ternate, and rarely with porrecto-ternate, or spiculated porrecto- 

 ternate spieula. Interstitial membranes — tension-spicula acerate, 

 slender, few in number. Retentive spieula attenuato-stellate, com- 

 paratively large, and very numerous ; radii few in number, and fre- 

 quently incipiently spinous, and rarely with large cylindro-sphero- 

 stellate spieula with radii apically spinous. Ovaria spherical, rather 

 small and very numerous. 



Colour in the dried state cream -white. 

 flab. Mexico (Mr. Thomas lngall). 

 Examined in the dried state. 



The exterior form of the specimen is very like that of the large 

 Neptune's-cup sponge with the interior space nearly filled up to the 

 brim. It is 5| iuches in height, and its greatest diameter is about 

 4 inches. It has no apparent base, but has evidently been supported 

 by several points of attachment to the stems of small fuci or zoo- 

 phytes, amidst which it has been developed. The external surface 

 is very irregular, being covered with large irregular nodular pro- 

 jections nearly an inch in height, and from half to three fourths 

 of an inch in diameter. There are several deep indentations or pits 

 iu its substance ; and the terminations of two of these on opposite 

 sides of the sponge have met and formed a passage completely 

 through it. Within these deep indents the oscula appear to be 

 congregated ; and there are also a considerable number of them on 

 one side within the terminal cup of the sponge. The greater portion 

 of the surface of the sponge is denuded of the large primary series 

 of defensive spieula ; but in one of the deep indentations they remain 

 in situ ; and on a large portion of the thick rim of the cup they are 

 present, crushed down into a compact layer, intermingled with con- 

 fervoid vegetation, to which it is most probable we are indebted for 

 their preservation on that portion of the sponge. That the whole 

 of the external surface has been armed with thes? large spieula is 

 amply proved by their basal portions remaining imbedded in every 

 part of the crustular dermis that has been examined under the mi- 

 croscope. The secondary series of external defensive spieula are 

 imbedded near the outer surface of the dermal crust, their distal 

 points projecting numerously, but to a very short distance, beyond 

 the dermal membrane. The porous areas are abundant on the 

 greater portion of the exterior surface of the sponge ; to the unas- 

 sisted eye they appear like a series of impressions made by the point 



