"Vol 



[N 



f India. 19 



f 



ted and 

 form 



Weber ; but i 



skeleton fascia. Manj of tW amphioxi are\s° loC br ,^^^^^^^^^ 

 as long as the skeleton spicules, into which they develop as is 



■ hfbod"? thr '''^'' Intermediate stages) b/a thSiLg o 

 the bodj of the spicule which does not affect its extreme ends 



ton" spicui:''; ttr"''^ '^^l ^^^^^^^^^ ''-^ cha-acteHsti" Met 

 ton spicule of the species. I was at first inclined to regard the 



rX''T; micrffcr'^'" '^^''"^T^ ^^ «^'«^-*- mic^^Set 

 latliei as microscleres varying from extremely minute filamprif 



rWererBlVtf ^"'^^ ^^^^^-^ ^^^^^ ^^^ ^ th^k'asThe 

 lue ascieres. ±}ut this view is precluded by the fact that intpv 



tlie one hand and between the amphioxi as a whole and tlia 



taXn's inTf 'r tf '"' "-'"^-jy "een in°c:.;:;i£5 



tue skeleton, on the other, occur frequently and th-Lt ih^ 

 amphioxi are most abundant in parts of^he Sponge in th S 

 either active firrowth or acfcivfi,.>..r,.l,-o — .^ „„:j_^_x ^ , ., ^, " 



either active growth or act.ve .han^rr^o^t vidTntTwhilelh:;: 

 TF}:.rr7,''-t °=<^- l-^ neithe/of these re.ion. -oeri it I ! 



reu'ions generally lie 

 err ' '" r' "^•^^^'^ «V*'^ skeleton, ready to be affixed to it by the 

 secretion of spongin when thej shall be mature. That growth s 

 actiye on the external surface of the Sponge is proved bf Z fact 

 that snail-shells which chance to come in contact with Tt are 

 rapidlj overgrown by it ; while that considerable chancres t^ke 

 place in the neighbourhood of the gemmules is eyident fro m the 

 structure of these bodies. The amphioxi near the surface ar^ not 

 in the dermal membrane but below it. In spite of JhrWc 

 amount of spongin present in the skeleton, the membrane con 



