9 6 
TH. MORTENSEN, 
(Schwed. Südpolar-Exp. 
actinal side the primary tubercles are somewhat larger. The labrum is very pro- 
minent; it reaches backwards to the middle of the second ambulacral plate; in one 
specimen (male), however, the first adjoining ambulacral plate of ambulacrum I is 
very elongate, and the labrum does not reach beyond it. In this specimen the right 
sternal plate is the largest, the suture between the two sternal plates continuing into 
the suture between the first and second plate of the inner series of the left ambu- 
lacrum (I). The plastron is rather narrow, though less so than in A. Lorioli; the 
suture between the two sternal plates is distinct. 
The apical system (Figs. 26—27) is like that of A. Lorioli (the specimen in 
this collection); the madreporic plate separates the posterior genital and ocular 
plates, but does not reach beyond the posterior ocular plates. Only three genital 
pores are developed, the right anterior one is wanting; they are small in the male, 
rather large in the female. 
Fig. 27. 
Figs. 26 — 27. Apical system of Amphipn. Koehleri , male (26) and female (27). s /r. 
A most conspicuous difference from A. Lorioli is found in the position of the 
periproct; it is placed on the posterior, vertical end of the test, so that it cannot 
be seen from the actinal side; it is more or less sunken. It is somewhat variable 
as to size and form, but, upon the whole, it may be said to be a little elongated, 
pointed in one or both ends; it is covered by small plates in the usual way. 
The peristomial region is somewhat sunken; the first interambulacral plates not 
excluded from the peristome, which latteris of the usual size. The plates of the peri- 
stome are covered with miliary tubercles carrying pedicellariæ. 
The spines are rather long and coarse, of uniform length, covering the petals 
and the apical system completely; those of the actinal side are a little longer, those 
of the plastron are flattened at the point but not widened. The miliary spines are 
slightly curved and clubshaped. The colour of the spines is brown, as is upon the 
whole the colour of the specimens as preserved in alcohol. 
The tubefeet of the odd anterior ambulacrum are like those of the paired petals, 
sack-shaped gills, generally without spicules and without sucking disk or rosette plates. 
