1905.] SPONGE CLATHRINA CONTORTA. 11 
monaxon or an abnormal triradiate (text-fig. 3, 3); probably it 
is both! My friend Mr. Alford has also found, in the slide of 
Topsent 12 e, four abnormal monaxons which have additional rays 
growing out laterally and thus become triradiates (text-fig. 6, 
9a-9c). In one of these (96) the three rays are approximately 
equal in size and meet at the angles of an ordinary triradiate. 
For all these reasons I consider there is much to be said for 
regarding the monaxons of contorta as secondary monaxons 
derived from a triradiate system by suppression of one ray and 
hypertrophy of the two remaining, which become piaced in the 
same straight line, or nearly so. 
The numerical variation in the monaxons is not less re- 
markable. In some specimens scarcely any monaxons are to be 
found; in others they are extremely abundant. Thus in a 
specimen recently examined by me, I took a fairly large piece of 
the sponge, separated the spicules with Eau de Javelle, and 
mounted all I could get up with the pipette, covering three slides. 
After prolonged searching I found five monaxons to many 
thousands of triradiate systems. In another specimen in which 
IT could find no monaxons, Mr. Alford by careful searching found 
two. It is often extremely difficult to be certain if a specimen 
has monaxous or not. Mr. Alford has kindly undertaken for me 
the task of counting the numbers of each kind of spicule found 
in different specimens, with the following results :— 
Triradiates. Quadriradiates. Monaxons. 
| Kind of | 5°21 2 
Specimen. | Actual |—Per- | Actual | Per- | Actual | Per- Moerene of 
number | centage | number | centage number centage servee: | Spicules. 
counted.'of whole.| counted. |of whole. counted. of whole. | 
sea “yi Pace aerial Pn =o 
Alea 93 | 3-278 27 | 96:128 5 Large. | 2837 
(Zz 3.a-3h). 3 | 3278+] 272 23+) 17 599+ arge. 3 
MIO. 311 | 8304+] 3423 |91402 | 11 | 204+) Lar 3745 
(z2a-2h) +| 342 02 aes ae || arge. 3) 
INI@ B soosos 886 |12°512+| 2658 |86158+ 41 | 1329+ |Very large.| 3085 
No. 4 o47 | 5835+/ 3965 |93668+ 21 | “496+ Very large.| 4233 
y 
(Plate I. B). | | 
IN@s 6) coonee 146 5'144+| 2686 | 94°644+ 6 | ‘211+ | Gigantic. | 2838 
No. 6 | 
Cow 267 |10°349+] 2188 |84:806+, 125 4-844 | Gigantic.) 2580 
12 e). | 
Total for ; : Ad 
Spacing, } 1450 7506 | 17647 | 91°35 221 1144 19318 
These results were obtained in the following way :—‘“ Hach 
specimen was put into Eau de Javelle to separate the spicules, 
and after careful washing, and being allowed to stand for some 
