322 rr - J AMES-CLARK ON THE AFFINITIES OF SPONGES. 



neck, which flares (e 1 ) slightly at the aperture. It sometimes, however, is slightly pointed 

 at its base where it joins the pedicel (pd). When not filled by the head (fig. 32, i) of the ani- 

 malcule, the neck and the sharp margin (c 1 ) of its aperture may be clearly distinguished from" 

 the collar (b) which rises just above them ; but very frequently this discrimination is attended 

 with a good deal of difficulty, because when the body presses closely at this point it over- 

 laps the margin in question, and obscures it. The pedicel (pd) is not much longer than the 

 calyx, and joins the latter with little or no expansion. It is colorless like the calyx, mod- 

 erately slender, of a uniform diameter from top to bottom, and appears to be solid and 

 homogeneous in texture. Figure 32 a represents one of three bodies which were found in 

 the midst of several living animals of this species, and which had every appearance of being 

 the deserted calicles of the same, with a collapsed aperture. In the next species (S. am- 

 phoridium) the deserted calicles (fig. 37, c) were found so numerous among those which were 

 occupied, and moreover retaining the shape of the latter so perfectly, that there could be no 

 doubt that the calyx is not only a separate organism apart from the body-wall, but also may 

 be as readily vacated as that of Cothurnia or Vaginicola. 



§ 9. Salpingceca amphoridium, nov. sp. 

 (Plate IX., figs. 37-37 d .) 



Although this species bears a strong resemblance to S. marinus (§ 8), there are sevei'al 

 prominent points of difference between the two. S. amphoridium is a fresh-water form, and 

 appears especially to frequent old specimens of Zygnema and other filamentous Algce. It is 

 very common in such places, and lives in more or less crowded groups. Excepting the main 

 part of the body it is very transparent, but not so faint as S. marinus. It varies much in 

 size, even down to half that of fig. 37 a . Like its marine congener it always occurs single, 

 and never with a trace of a pedicel to the calyx (c, c 1 ). As a compensation for this, if one 

 may use the expression, it has a long neck, which is frequently seen bending from side to 

 side (fig. 37 b , /) with a gentle motion, and apparently in search of something. 



The body is gray or greenish yellow in color, which fades in the neck (i) and disappears 

 altogether in the collar (b). In its general aspect the body, with its collar, might be com- 

 pared to a wine-glass with a long stem and a globose pedestal. The globose part is the pos- 

 terior half ot the body, and the stem is its neck, or anterior half, which tapers rapidly from 

 the main part to one quarter or one fifth its diameter, and then gradually widens to nearly 

 double that thickness at its front, where the collar is set on. The front is truncate, or rises 

 into a low cone, upon which the flagellum (ft) is based. The posterior half of the body 

 usually fills the bottom of the calyx (c), but the rest and the neck (i) stand off from it at a 

 very appreciable distance. In this respect there is a marked difference between this species 

 and iS. marinus (§ 8). In the latter we might say that the body is suspended from the aper- 

 ture of the urceolus, but in the former it rests on the bottom of the calicle. Not infre- 

 quently, however, the whole body of this species lies loosely within its calyx (fig. 37). 



The collar (b) is an excessively hyaline, filmy membrane, whose distal margin (b x ) is so 

 extremely delicate as to almost defy detection with the highest powers. In the latter 

 respect it is a more difficult object of research than that of S. marinus. Generally speaking it 

 may be described as obconical, but with greatly varying degrees of width. In this relation it 

 agrees perfectly with that of S. marinus, and therefore need not be redescribed here. At its 



