1863.] DR. J. S. BOWERBANK ON THE SPONGILLIDiE. 451 



face of the water about a month after the first heavy rains of the 

 S.W. monsoon have fallen." 



Spongilla Baileyi, Bowerbank. 



Sponge coating ; surface smooth ? Oscula and pores inconspicu- 

 ous. Dermal membrane spiculous ; spicula fusiform i-acerate, en- 

 tirely spined ; spines of the middle cylindrical, truncated, very long 

 and large. Skeleton- spicula subfusiformi-acerate, rather slender. 

 Interstitial membranes spiculous ; spicula same as those of the der- 

 mal membrane. Ovaria globular, smooth, abundantly spiculous ; 

 spicula arranged in lines radiating from the centre to the circum- 

 ference of the ovary, birotulate ; rotulse irregularly and deeply cleft 

 at the margins, incurvate ; shaft very long, cylindrical, entirely 

 spined ; spines conical. 



Colour, in the dried state, dark green. 



Hab. A stream on Canterbury Eoad, West Point, New York 

 {Frof. J. W. Bailey). 

 Examined in the dried state. 



I am indebted to the late Prof. Bailey, of West Point, New York, 

 for my knowledge of this interesting species. In a letter to me, 

 dated .30th Nov. 1856, he writes, "The only bit oi Spongilla I have 

 been able to find in my collection is from a small mountain- stream 

 near West Point. It was picked from a small pebble in a pool 

 which the stream formed as it crossed the road. It attracted my 

 attention, I believe, as being of very small size to have gemmules. 

 I send it just as it was gathered." 



The specimen was in an oblong packet less than an inch in length ; 

 it contained a few fragments of Spongilla, the largest of which was 

 about two lines in diameter. It was full of gemmules, and in fine 

 condition for examination. 



The structural peculiarities of this Sponge are very remarkable ; 

 it belongs to the tribe of which all have birotulate spicula imbedded 

 in the coat of the ovarium and disposed in lines radiating from the 

 centre to its circumference. It has the birotulate spicula four or five 

 times as long in their proportions as those of the ovaria oi S.Jluvia- 

 tilis. Its nearest congener is the East Indian species Spongilla 

 plumosa. Carter ; but it differs in structure from that Sponge, both 

 as regards the tension- spicula and those of the ovaria, the rotulse in 

 Spongilla Baileyi being cleft or dentated to very near the centre, while 

 those of <S. plumosa are entire, excepting a slight marginal crenation, 

 and the shaft also is considerably shorter than in those of S. baileyi 

 when fully developed. 



I observed these beautiful spicula in every stage of development, 

 from the slender smooth shaft with only slightly clubbed termina- 

 tions to the abundantly spinous shaft and fully produced rotulse, just 

 as those of S. plumosa are represented in pi. 26. figs. 18-20, in the 

 ' Phil. Trans.' of the Royal Society of London for 1858. 



The tension-spicula of the dermal and interstitial membranes are 

 remarkably characteristic. They are very small, and require a power 

 of about 700 linear to define them well. They are very similar to 



