
HALE—AUSTRALIAN CUMACEA 67 
on each side. When these depressions are fairly pronounced, their hinder end is 
marked by a slight emargination of the dorsal outline and their lateral limits form 
a fold running from the middle of the length of the carapace to the posterior ends 
of the pseudorostral sutures, then approximately along the curve of the latter. 
The smooth appearance of the species in Section 1 of the key is scarcely, if at all, 
affected by these slight folds, and they are not to be confused with the true lateral 
ridges found in many forms of Section 2. 
Again, in some species of Section 1, the edge of the short shallow gutter often 
present back of the antennal notch may be slightly emphasized to form the so-called 
antennal ‘‘ridge’’; this is faint, but can be discerned by rotating the stage so as 
to vary the lighting. 
The development of antero-lateral tubercles, one below the other, is a common 
but not universal feature in Section 2; there may also be one or (rarely) two 
postero-lateral elevations on each side. Both antero-lateral and postero-lateral 
tubercles may be crossed by carinae (into which they merge) or only one such 
ridge may be present; these transverse carinae may continue across the back 
(exsculpta, persculpta, tribults, australis, ete.). 
Recognition of the basie arrangement of the ridges and tubercles in the 
exsculpta group may present difficulties in some cases, unless juveniles as well as 
adults of both sexes are studied, a consummation devoutly to be desired but rarely 
possible. In the young of tribulis, for instance, all the ridges enclosing the de- 
pressed quadrilateral area on the side of the carapace are distinct, although the 
tubercles are small. The juvenile is used in fig. 2 to illustrate the plan of sculp- 
ture and the terminology. 
The pair of small depressions, sometimes deep pits, at the base of the frontal 
lobe, have been referred to by Zimmer. 
Elevation of the mid-line of the dorsum to form teeth is rare; it occurs in 
unicorms Calman, bicornis Zimmer, and unplicata Calman, 
Pedigerous somites. The exposure or concealment of the first somite seems 
to be of no special taxonomic import, nor do the marginal plumose hairs which 
Zimmer comments upon. The shape of the somites and their carinae are best de- 
seribed by illustrations, as is also the often distinctive contour of the dorsum of 
the second somite. 
Pleon. The abdomen is fairly uniform in structure. It may be unusually 
lone (stbogae, cana) or short (gtbba) ; robust (male of some species, see for in- 
stance sheardi) or slender and flexible (pinguis), Articular pegs are usually, if 
not always, present but may be so inconspicuous that they are detected with some 
difficulty. 
Peracopods. Although the thoracic appendages exhibit no gross variation, the 
proportions of the joints are constant in adult or almost adult specimens of a species 
and there are other features worthy of note. 
The terminology used in the present descriptions should be mentioned here. 
While recognizing its reasonableness, I have not adopted Hansen’s nomenclature, 
but in order to avoid confusion and to facilitate comparison with earlier diagnoses 
have adhered as previously to the widely used coxa, basis, ischium, merus, carpus, 
propodus and dactylus for the joints 1 to 7 of Stebbing, ete. In Hansen’s in- 
terpretation of the limb joints as found in most Peracarida, ischium, as here 
used, = pretschium; merus = ischium; carpus = merus; and propodus = carpo- 
propodus. It might perhaps be simpler to follow Stebbing’s practice, but there 
again, his second joint equals Hansen’s third, and so on. 
The inner apical ‘‘angle’’ of the basis of the first peraeopod is in some species 
produced to form a subtriangular tooth-like process which may be comparatively 
pronounced (see strigilis, cretata, granulosa, formosae, herdmani, hornelli, ete. 
Almost always a long plumose seta is present at the external apical angle of this 
