31 G H. JAMES-CLAEK ON THE AFFINITIES OF SPONGES. 



highly refractile pellets (fig. 24 a , d), close to the base of the flagellum. The digestive 

 vacuoles are quite conspicuous, and frequently very large ; but they never have been ob- 

 served to be so numerous as to obscure the view of the interior of the body. 



The contractile vesicles (cv cv) are two quite conspicuous globular organs, which lie close to 

 the surface, and in the posterior third of opposite sides of the body. Occasionally three (fig. 

 10, cv) of these vesicles are found together, but it has always been evident at such a time 

 that the body was preparing for fissigemmation (figs. 9, 10), and that the increase in num- 

 ber of these organs arose from the fact that one of them had already undergone self-division. 

 In another genus (Salpingoeca. 8. marinus, nov. sp. figs. 28, 29, 30) no less than four contrac- 

 tile vesicles (cv) have been observed to arise from two, under the same circumstances. 



The systole of each vesicle of Codosiga occurs regularly once in half a minute, and usually 

 that of one alternating with that of the other. Both the systole and the diastole proceed 

 very deliberately, each, however, not occupying more than a few seconds. During the in- 

 terval between the end of the diastole and the beginning of the systole the vesicles have a 

 rather irregular, indefinite, spheroidal outline, but just at the moment of systole they assume 

 a sharply defined and perfectly globular shape, and raise the surface of the body into a quite 

 perceptible bulge. During this momentary expansion a vesicle equals at least half the 

 greatest diameter of the body. 



The reproductive organ — if we are not mistaken in our interpretation — is seated at the 

 posterior end of the body, behind the contractile vesicles. It is a globular, highly transpa- 

 rent body (figs. 23, 24, n), and sometimes almost fills the space on each side of it. That it 

 is solid, and not a mere vacuole, appears conclusive from its resilient action after beino- 

 indented by the expansion of the contractile vesicles. It should be mentioned that this 

 body was not observed in the fresh specimens which were collected in December, but ap- 

 peared to be constant in some stale examples which had been kept on hand for two or 

 three months. 



The peduncle (fig. 8, pd), or main support of the colony, and the pedicels (pd 2 ) or immediate 

 bearers of the individuals, share in the general gamboge yellow color of the latter, and also 

 in their vitality. The latter statement has been verified fully in regard to the pedicels, by 

 seeing them split down to their bases after the body proper has undergone self-division ; and 

 in regard to the peduncle, although only one observation was made, and the splitting was 

 followed in its slow course downward for only a short distance, it was evident, from its much 

 more than usual thickness, and the presence of a distinct median furrow which extended to 

 its very base, that it eventually would divide into two stems. The length of the peduncle 

 varies from a mere disc, when it begins to develop from the base of some newly settled 

 monad, to five or six times the length of an individual. It always carries a single body until 

 it is at least three or four times its length (figs. 9, 24, 24 a ), and frequently much longer; 

 but in the latter case it was sometimes observed to arise from the falling away of one of the 

 resultants immediately after self-division occurred. It has a uniform thickness, or occa- 

 sionally the slightest possible taper, from base to apex ; and appears to be solid and homo- 

 geneous in texture. It is apparently inflexible, and even when carrying a single body is 

 united to it at a sharp angle with the longer axis of the latter (fig. 24 a ). 



Fissigemmation, This is the only process of reproduction which has been observed. 

 Several instances of this kind were partially followed through in an incidental way, and two 

 complete courses were carefully noted and drawn within a half hour of each other. The 



