212 



GEODINELLA ROBUSTA. 



former had a diameter of 50 and the part of the spicule from which it arose 

 was 42 fi thick. The latter had a diameter of 43 /x and the part of the spicule 

 from which it arose was 40 fi thick. Occasionally, but very rarely, rhabds with 

 a clade-shaped protuberance, resembling anamonaenes (Plate 4, fig. 10) occur. 



In the rhal3ds with undulating surface the irregularity is probably caused 

 by some inequality in the action of the silicoblasts during growth. The monaene- 

 like forms just referred to are altogether abnormal, probably pathological. The 

 rhabds with the rounded and annular protuberances I am inclined to consider 

 as spicules transitional between regular rhabds and teloclades. 



The teloclades and teloclade-derivates (Plate 1, figs. 1-11, 13-15, 18-20; 

 Plate 4, figs. 23, 25). The cladome of the teloclades is always reduced. This 

 reduction is chfferent in degree and in kind in the three varieties. In var. 

 carolae the teloclades have entirely lost one or two of the triaene-clades ; in the 

 two others invariably two. In var. megaclada the single remaining clade is often 

 quite long. In the two otlier varieties the clades are always very short. Thus 

 var. carolae possesses some diaenes besides the monaenes, both with short 

 clades, var. megaclada only monaenes, many of which have a rather long clade, 

 and var. megasterra only monaenes, which always have a short clade. In all 

 three the cladome is usually simple and situated at or near the cladomal end 

 of the rhabdome. Besides these ordinary teloclades, teloclade-derivates with 

 more cladomes than one, and with clades arising some distance from the end 

 or reduced to insignificant protuberances, are met with. 



The diaenes and monaenes of var. carolae (Plate 1, figs. 5-11) have the 

 same dimensions. The monaenes (Figs. 6, 9-11) are much more numerous 

 than the diaenes (Figs. 5, 7, 8), particularly in the specimen from Naha Bay. 

 The rhabdome is 1.1-1.7 mm. long and at the cladomal end 26-40 /j. thick; 

 it is generally straight or slightly curved, rarely (Fig. 6) angularly bent, and 

 usually attenuated towards the acladomal, blunt or, more rarely, pointed end. 

 Sometimes (Fig. 5) this attenuation is so slight that the rhabdome appears 

 nearly cylindrical. In such spicules it is simply rounded off at the end. The 

 cladome is generally quite terminal (Figs. 5-9, 11), rarely situated a little below 

 the end of the rhabdome (Fig. 10). The clades are 30-70 fi, usually 40-55 p. long, 

 generally quite straight, irregularly conical, and pointed (Figs. 5, 6, 8-10), 

 or, more rarely, cylindrical and rounded terminally (Fig. 11). In the diaenes 

 a pointed clade may be associated with a rounded one (Fig. 7). The clades 

 enclose angles of 93-130° with the rhabdome, so that some of these spicules ap- 

 pear as orthodiaenes or orthomonaenes (Fig. 10), others as plagio- or pro-diaenes 



