366 
HYALONEMA (PHI ALONEM A) PATE RIFERUM. 
base 4-6 n, maximum 8-27 n; and in form F base 3.5-6 fi, maximum 7-16 n. 
The maximum thickness of the distal ray, together with the spines, is in the 
ordinary pinules with laterals of moderate length usually 8-16 n; distal rays 
with a maximum thickness of only 6 n or less are found only among those forms 
with long laterals, which pass into the microhexactines. The lateral rays are 
in the forms A and B, according to Wilson ( loc . tit.), pointed and nearly or quite 
smooth. In the forms C, D, E, and F they are also usually pointed, but smooth 
only exceptionally ; as a rule they are provided with sparse, but rather large and 
conspicuous spines. Sometimes I observed lateral rays with much larger and 
more numerous spines which, in respect to spinulation, resembled the distal ray. 
The lateral rays are in the forms A and B, according to Wilson (loc. tit.), 
30-40 fj. long, in form C 13-44 fi, in form D 16-100 n, in form E 24-54 /*, and in 
form F 26-63 /x. The pinules with lateral rays more than 50 n long are mostly 
transitions to the microhexactines. In the ordinary pinules a sixth proximal 
ray is present only quite exceptionally, and here hardly ever more than 30 n 
long; in the pinules transitional to the microhexactines a proximal ray is gen- 
erally met, and in these it attains a length of 50-100 n. In regard to the 
spinulation, the proximal rays usually resembles the laterals. In some of the 
forms transitional to the microhexactines, the proximal ray is spined in a similar 
way to the distal. 
The pentactine pinules with elongated distal ray (Plate 52 , fig. 15). The 
distal ray of these spicules is in the forms A and B examined by Wilson (loc. 
cit.) 300-400 fj. long, in form D 240-315 n. In forms C and F I observed only 
very few pinules of this kind. In these the distal ray was 350 n long. In 
form E I failed to find any pinules of this kind. I ascribe the absence of these 
spicules in this form and their scarcity in the preparations of forms C and F 
to the fragmentary condition of the specimen of these forms. In the forms 
C, D, and F the distal ray is 4. 5-6. 5 n thick at the base, conic, and generally 
somewhat curved. It terminates in an exceedingly long and slender, spineless 
terminal cone. Its middle-part bears small spines inclined towards the tip. 
Its maximum transverse diameter, together with the spines, is 5-14 n. In 
forms A and B, examined by Wilson (loc. cit.), the distal ray is similar. The 
lateral rays are pointed or, more rarely, rounded at the end. In the forms 
A and B, examined by Wilson (loc. cit.), they are 40 n long, in the forms C, D, 
and F, 15-38 n. 
The diactine pinules (Plate 52 , fig. 16) appear as anisoactine, centrotyle 
amphioxes with numerous spines on their distal ray, and occasionally also a few 
