278 WILSON. [Von IX. 
PAGE 
II. ADULT STRUCTURE AND GEMMULE DEVELOPMENT OF TEDANIA 
BRUCEI, N. SP. 
Bia CASTS Ui TAD ee essen wc cnc tesa eee econ ace ret sees ea epee cchne sates cers faveveneeassematrrerenaeacereees 320 
Collecting and Emobryological Methods..............cceesvn cere eens ereeee 325 
2. DEVELOPMENT OF THE SWIMMING LARVA.........-.::::csccseccssssesceees 32 
POV IVOTLON Of ME CTIVTILULLES ns acumen ide ccs aureiseaseeneewecesseas osanaanevat races center aee 327 
Development of gemmutle into swimming larva.........-..-..eeeene 329 
BSLV UCCUV ERO, LIE SLULILTILUML DLAI aan setae es nee nanc cee aearzs esate tee 331 
Br Mi TAM ORIPEIO SIS tescsseeterseetatar enecaeteesteenveseeentcccedeteceenarenaraatectee eee ce eens 332 
ALLOCHIENE 2. cos bein scsns cana ste se vests sanenssntsssos cotgeteasarstacnesso4eh sous caten seed eee 332 
Ectodermal membrane and peripheral mesodermic 2one.............. 335 
COMGLE SY STCND eae a BD eae casa os settee caer soe vee eset seaae ee 337 
III. ADULT STRUCTURE AND EGG DEVELOPMENT OF TEDANIONE 
FOETIDA, N. G. 
Moe ADIT 62205, sue csacd oon scares scasst Visaceseeaapeatesseecacleea neste sencetesnetcaseaten see scate teas 338 
2 ADE VEL OP MIE NS. Neos ceeccoce tance cucesctsncnenees featteaten saeer a tet acces saacgo ecco Nees 341 
IV. EARLY STAGES IN EGG DEVELOPMENT OF HIRCINIA ACUTA............ 346 
V. REMARKS ON THE MORPHOLOGY OF SPONGESG........2..-:csecesceecsessseseseeees 348 
Evidence from comparative anatomy as to sponge Phylogeny..........-..-+. 350 
Embryological evidence as to sponge DRYlOQENY..2....c...ceceeeececeesesereereees 357 
OVESE Of CHE OLY HERG ao ota cues steeds ster sun cosenne sadtascee eee ae renees tera aee nate cree 362 
VI. REMARKS ON THE GEMMULE DEVELOPMENT OF SPONGES. 
1. ASEXUAL DEVELOPMENT IN GENERAL OF THE SPONGES.......... 364 
2. COMPARISON BETWEEN THE EGG LARVA AND GEMMULE 
IVARVA SOR MORETCTOUS MORO NGS scescreteteee: ae ecetceceret teeeree snes seee seam 368 
Resemblance between the two kinds of lar vae............-0.0vereeeereee 368 
GCOUSENOf LCI CSCUEOLLILG Cm eee amie tv siee sees tart omnceceserternsenrectriceneteaenen ets 370 
THE observations described in the present paper were begun 
more than four years ago, when as Bruce Fellow of the Johns 
Hopkins University I was permitted by the directors of the 
fellowship to spend a considerable part of the academic year in 
the Bahama islands. For their kindness in complying with my 
wishes in this matter I thank them heartily, and trust they may 
find in the following pages some justification of that pleasant 
excursion. 
The investigation has been subject to many interruptions. 
On returning from the Bahamas it was prosecuted for a time 
in Professor Brooks’s laboratory, but other duties incident to 
my connection with the U.S. Fish Commission interfering, it 
was laid aside until midsummer, 1890. The Commissioner, 
Hon. Marshall McDonald, feeling that any enlightened attempts 
