II. JAMES-CLARK ON THE AFFINITIES OF SPONGES. 315 



This phenomenon is most singularly exemplified hy the creature before us now, in its al- 

 most indistinguishable resemblance to a genuine calyculate Flagellifer (iSalpingceca marirms, 

 figs. 28-32 a ) which abounds in our marine waters. This similarity arises chiefly from the 

 fact that the urceolus (figs. 28-32, c) of the latter has an oval shape like the body of the 

 former, and is constricted so closely at its aperture (c 1 ) as to present the appearance of beino' 

 continuous with the high campanuliform collar (b) which projects from the front. Usually, 

 however, the body proper of this animal (Salpingatca marinus, no v. sp.) lies loosely within, and 

 considerably withdrawn (fig. 28) from, the parietes of its calyx; but occasionally, in older 

 specimens, it completely fills (fig. 31) its sheath, and then it is next to impossible to dis- 

 tinguish it, in this respect, from a Codosiga. In a sessile, fresh-water species of Salpingozca, of 

 the urceolate type (S. amphoridium, figs. 37-37 d ), the resemblance to Codosiga is almost as strong, 

 but the difference is as equally marked. 



The flagellum (figs. 8, etc., fl) is the only prehensile organ which Codosiga possesses. It 

 arises from the middle of the low truncate cone (/r), which constitutes the front, and conse- 

 quently within the campanulate collar (b) ; reminding one of the curvate style of a labiate, 

 monopetalous flower. It is usually rigid, excepting at the tip, which is constantly occupied 

 in throwing particles of various kinds toward the mouth (m) by vigorous, spasmodic incur- 

 vations, or jerks. At its basal half it is slightly curved toward the longer side of the body, 

 but gradually reverses the arc and, assuming a much stronger bend in the opposite direc- 

 tion, terminates abruptly, and far beyond the edge (b 1 ) of the collar, with about the same 

 thickness as at its base. It is a very conspicuous organ, and therefore its whole sigmoid 

 length may be studied with any amount of detail that could be wished for. The plane of 

 this sigmoid curve is a direct continuation of that which passes through the opposing longer 

 and shorter curves of the obliquely oval body. Calling to mind now what has been said in 

 regard to the direction of the curve of the flagellum of the respective individuals of the 

 colony, it will be seen that if these planes are projected inwardly and downwardly, at the 

 same time passing along the pedicels (fig. 8,pd 2 ) of each body, they will all meet at the 

 main stem (pd). 



Besides being used as an organ of prehension, the flagellum is occasionally devoted to other 

 purposes ; for instance, to act as a scavenger by whirling in a gyratory manner, and thus 

 clearing the area, within the collar, of fcecal matters which have been ejected from the anus 

 at a point near to, or perhaps coincident with, the. mouth (in). At other times it acts as an 

 organ of propulsion during the act of natation (fig. 23), when one of the resultants of 

 self-division breaks loose from the colony and seeks another point to settle down upon and 

 secrete its stem. During this wandering life of the monad it swims — at times very rapidly 

 — with its basal end (fig. 23) preceding it in the direction of its course, and the flagellum 

 [fl) following behind, and vibrating in rapid undulatory and gyratory curves, as if it were 

 the screw propeller of some subaqueous vessel. 



That the month (figs. 23, 24, 24 a , m) is situated near the base of the flagellum (/) is ren- 

 dered certain by the fact that particles of food are thrown by that organ directly against 

 the area (//•) upon which it is based, and are taken within the body somewhere in that re- 

 gion ; but, on account of the minute size of these morsels, and the rapidity with which they 

 are swallowed, it has not been possible to determine precisely at what point The position 

 of the anus, which, as I have already suggested, may possibly be coincident with the mouth, 

 is easily determined, even to the narrowest limits, as the feecal matter is discharged in large, 



