Zoology.'] NATURAL HISTORY OF VICTORIA. [Crustacea. 



Our plate 160 illustrates a remarkable variety of the typical 

 A. serratus of tlie MiuTay, common iu the Yarra and its numerous 

 affluents flowing southwards into the sea of the south coast of the 

 colony ; and as very few of the inhabitants of these river systems 

 are identical (most of the species and many of the genera being 

 dissimilar), this form is worthy of special note. It is usually less 

 than half the size of the Murray individuals, being usually only 

 five inches and rarely six inches long ; it further differs in the 

 whole thorax and abdomen above being of an intense Prussian- 

 blue color, the spines, chelfe, and under surface ivory-white, with 

 the membrane of the joints red. All the proportions and the 

 nimiber and disposition of the spines seem to me to agree so 

 closely with the large pale Murray form, that, although so unlike 

 at first glance, I have no doubt the southern race is merely a 

 variety, which, for convenience of reference, may be distinguished 

 by the name of the river in which it is chiefly found, fi'om its 

 mouth at Melbourne to its highest branches. The colors of those 

 from the Watts River are particularly intense. 



Explanation of Fioitees. 



Plate 160. — Fig. 1, male specimen, yiewed from above, natural size. Fig la, same, riewed 

 from below, showing the male openings in the base of the bind pair of legs, and the absence of 

 appendages to the first abdominal segment. Fig. 16, side view of same. Fig. le, top of head, 

 magnified two diameters, to show details of rostrum. Fig. \d, side view of portion of head, 

 magnified two diameters, to show proportional dimensions of rostrum, antennary scale, and 

 basal joints of antennae. Fig. Ic, one of the abdominal appendages, magnified three diameters. 



Note.— The color of the under surface, and chelse and spines of upper surface, are rather too dark, and should be oJ 

 an Ivory-white with a slighter Drown tinge. ^ 



Frederick McCoy. 



YOL. 11.— DzciDl XVI.— 2! [ 227 ] 



