
68 RECORDS OF THE S.A. MUSEUM 
joint and sometimes there is a shorter second apical seta, well separated from the 
first. 
The second peraeopods are remarkably uniform in structure; the proportions 
of the joints vary little, but the relative lengths of the spines, particularly those 
of the distal end of the dactylus, are useful. 
The third to fifth peraeopods, judging from the available specimens, and 
from reference to published figures, are similar in many of the species. Never- 
theless, in the proportions of the joints and the number and length of the setae, they 
sometimes prove an aid in separating closely allied forms but do not conform in 
the groupings governed by the structure of the carapace. For instance, tribulis, 
a highly sculptured member of the exsculpta section, has posterior peraeopods 
similar to those of mjobergi (fig. 3, K), a ‘‘smooth’’ species. On the other hand, 
globosa and pinguis fall naturally together, but their posterior thoracic appen- 
dages are considerably different (cf. fig. 3, E and J). 
Zimmer (1933, p. 334, fig. 2) described in detail the fifth peraeopod of Dias- 
tylis rathket, drawing attention to the fact that the spines (or setae) of the carpus, 
propodus and dactylus of the posterior legs constitute a sort of digging scoop or 
rake (see also Foxon, 1936, p. 382, and Hale, 1943, pp. 341 and 342. 
The following notes concerning the posterior peraeopods in Cyclaspis are 
based on the examinaton of twenty-nine Australian species which are available 
for study. Setae are usually present on the six distal segments of these limbs. In 
globosa, for instance (fig. 3, A), the inner face of the basis is provided with plumose 
bristles; the ischium bears two strong subapical setae, the merus has one; there 
is a fan of distal setae, approximating in number and length to those of the 
ischium, at the outer angle of the carpus and in this case an isolated seta on the 
outer margin ; a single seta is articulated at the outer angle of the propodus, along- 
side the base of the dactylus, which has a small inner seta. 
Other insignificant setae may be present; for instance, there is often a tiny 
bristle at the inner side of the longest carpal seta, and there may be one on the 
outside of the dactylus. The terminal joints of the posterior legs of thirteen Aus- 
tralian species are shown in fig. 3. 
The propodal seta is always single, curved in the same direction as the daety- 
lus and, except in simula (fig. 8, B), it is stout and reaches at least almost to 
the tip of the limb, sometimes far beyond it. The pronged fork formed by this 
seta and the dactylus is supplemented (again excepting simula) by a long seta at 
the outer distal angle of the carpus; this is as stout as the propodal seta and ex- 
tends to about the level of the tip of the last-named ; close to this are seated one to 
four thinner setae (successively decreasing in length and diameter if more than 
one is present) ; a few more widely separated setae may be present on. the outer 
and sometimes inner margin also of the carpus (fig. 3, J, K, N). 
These ‘‘fossorial’’ setae, and apparently always those of the ischium and 
merus also, are flexible, particularly in the distal half or third, where they are 
sometimes curled in preserved material (fig. 38, N). In the terminal half or third, 
the seta exhibits a slight narrowing and thence to the tip its chitin shows a dis- 
tinet spiral structure (fig. 3, D' and E1). 
C. simula (fig. 3, B) constitutes a type apart in that the sole armature of the 
limb is an unusually feeble propodal spine and a short plumose seta on the basis; 
the species is known from a single subadult male. 
Of the other available Australian species, prwinosa, spilotes, pinguis, cretata, 
cana, caprella, gibba, sheardi, cotton, strigilis, concinna, clarki, and granu- 
losa have only two carpal setae. In most of these the longest carpal seta and the 
propodal seta reach only to about the level of the tip of the dactylus, while the 
second carpal seta is rather feeble (fig. 8, C and D), or is not much more than 
half as long as the stouter one (fig. 3, Eand F). On the other hand, the propodal 
