10 ME. O. A. SATCE ON A EEMAEKABLE 



fusion of these two joints is complete, and the exopod appears to spring from the ischium " 

 (third joint). In Koonunga, therefore, the legs are chiefly flexed at the articulation 

 between the fourth and fifth joints, as is the case in the Euphausiacea and Decapoda, 

 instead of the fifth and sixth joints, as shown by Caiman to occur in Anaspides. 



The relative length of the several joints is seen to be in close agreement in the two 

 species by reckoning the second and third together in Anaspides as equalling the second in 

 Koonunga. It will be seen, therefore, that this does not mean any more than that what 

 is partly coalescent in one species is completely so in another. Dr. Hansen has adduced 

 reasons for using this character as a basis for classification, but it is certainly not reliable 

 in the present order, and I venture to think that Dr. Caiman's * definitions of his divisional 

 groups would be better without its inclusion, for it is not always easy to correlate the 

 several joints by numbers from the base. 



Abdominal Appendages (Pleopoda). — In the female the first five pairs are quite similar 

 to each other, except that they successively become a little shorter. They are used for 

 the purpose of swimming, and each consists of a short stout basal joint followed by a 

 longer one; then follows a long multiarticulate flagellum with each joint bearing two 

 long feathered setse. Thereis no vestige of a secondary branch (endopodite) as in Anaspides. 

 In the males the third, fourth and fifth are quite like those of the females, but the first 

 two pairs possess endopodites modified for sexual purposes (figs. 18, 19, & 20). The form 

 of these endopodites is almost identical with that observed in Anaspides. The first pair 

 is short and broadly spatulate, with the distal margin deeply incised, and the inner 

 margin distally bearing some coupling-spines (figs. 18 & 19). It lies underneath the body, 

 and is directed forwards between the last pair of thoracic limbs, with its deeply concave 

 surface uppermost, and when united by the coupling-spines to its fellow of the opposite 

 side it forms an efficient pouch, which, probably, serves the purpose of a receptacle for 

 holding the spermatophore after passing from the vas deferens, the opening of which is 

 on the first joint of the last pair of legs and thus quite close to it. The endopodite of 

 the second pair is exactly like that of Anaspides (figs. IS & 20) and forms a long two- 

 jointed styliform appendage ; the first joint with a row of coupling-spines, and the second 

 joint apically pointed, and hollowed out on its distal inner face to form a deep concave 

 area, which, together with that of the opposite side, forms a little pocket, and when 

 lying horizontally is located within the anterior spermatophore carrier. Each is articu- 

 lated, so that together they have power of movement downwards. By these organs a 

 spermatophore may easily be passed from the vas deferens to the receptacle formed by 

 the union of the first endopodites ; from this it can be received in the pocket formed by 

 the union of the second pair of endopodites, and from this it can easily be transferred to 

 the receptacle in the female, which is medianly situated on the sternum in front of the 

 last pair of legs, and behind the openings of the oviducts on the inner side of the first 

 joint of the filth pair of appendages of the peraeon. How the ova are fertilized is not 

 clear, nor is it known if the spermatozoa are filamentous or not. 



Immediately behind the second appendages there is a peculiar median appendage 

 arising from the sternum, which, in ventral view (fig. 20), is of sagittal form, the apex 



Ann. & Mag. Nat. Hist. (7) vol. xiii. p. 15G (1904). 



