370 HYALONEMA (PHIALONEMA) PATERIFERUM. 



8 fi. Their anchors are 17-30 fi long, usually one seventh to one fourth of the 

 whole spicule, 68-101 n broad, and composed of from seven to eight teeth. The 

 proportion of anchor-length to anchor-breadth is 100 to 273-429, on an average 

 100 : 339. The large macramphidiscs of form D (Plate 52, figs. 3, 4, 9, 10) are 

 100-318 M long, most frequently about 200 ix, and have shafts 10-22 ix thick, 

 rarely only 8 ix. Their anchors are 19-47 ^ long, usually one ninth to one 

 seventh of the spicule, 55-122 n broad, and composed of from six to nine, usually 

 eight teeth. The proportion of anchor-length to anchor-breadth is 100 to 222-420, 

 on an average 100 : 298. The large macramphidiscs of form E are mostly regu- 

 lar, but irregular forms also occur among them. The regular ones (Plate 50, 

 fig. 15; Plate 51, figs. 2, 17-22) are 105-265 m long, rarely as much as 334/^, 

 most frequently about 200 ju, and have shafts 14-23 yu thick. Their anchors 

 are 17-35 n long, usually one tenth to one seventh of the whole spicule, 62-109 

 ij. broad, and composed of from eight to eleven teeth. The proportion of anchor- 

 length to anchor-breadth is 100 to 276-500, on an average 100 : 361. The rare 

 irregular large macramphidiscs of this form (Plate 51, fig. 16) differ from the 

 regular by their anchors being longer and composed of less numerous and spirally 

 twisted teeth. The irregular large macramphidisc (Plate 51, fig. 16) is 116 m 

 long and has a shaft 20 fx thick and anchors 42 yu long and 54 fx broad. The large 

 macramphidiscs of form F are 103-188 yu long, rarely as much as 235 tx. The 

 frequency-curve pertaining to their length has two summits, a higher one at about 

 136.5 IX, and a lower one at about 164 yu. The shafts of these spicules are 11-18 /x 

 thick, rarely as much as 22 ,u. Their anchors are 17-30 fx long, usually one eighth 

 of the whole spicule, 66-105 /x broad, and composed of from five to twelve teeth. 

 The proportion of anchor-length to anchor-breadth is 100 to 320-430, on an 

 average 100 : 363. 



The small macramphidiscs (Plate 51, fig. 15; Plate 52, figs. 5-8) are similar 

 to the large ones and have, like them, a shaft which is cylindrical and of uniform 

 thickness throughout (Plate 51, fig. 15) or thickened towards the ends (Plate 52, 

 figs. 5, 7). The shaft is either smooth (Plate 52, fig. 6), or it bears a few low 

 tubercles scattered irregularly over its central part (Plate 52, fig. 8). The 

 anchors are generally one sixth to one third of the whole spicule in length, and 

 composed of from four to seven teeth; in the smallest forms there are four or 

 five teeth. The number of teeth in the two anchors of the same spicule is often 

 different. The teeth are similar to those of the large macramphidiscs above 

 described, but, particularly in the smallest form, more slender, relatively longer, 

 and more strongly curved. 



