ON THE ANASPIDACEA, LIVING AND FOSSIL. 497 
the water round the delicate leaf-like external gills attached 
to the bases of the thoracic limbs. 
The body consists of a head, bearing a pair of pedunculated 
eyes, and there follow apparently eight free thoracic seg- 
ments, six abdominal segments and a telson. The sixth 
abdominal segment carries a pair of expanded, backwardly 
directed pleopods, which form a powerful tail-fan. 
Paranaspides lacustris (text-fig. 1, and Pl. 11, fig. 2), 
from the Great Lake of Tasmania, although in its detailed 
TXT TG 2. 
Koonunga cursor, ¢, from a drawing by Mr. Sayce. x 16. 
structure very similar to Auaspides, differs very widely 
from it in external appearance, and in this respect it is 
probably the most aberrant of all the Syncarida, including 
the fossil forms. The body, instead of being deeply pig- 
mented, is of a transparent green colour, sparsely powdered 
with black dots; and there is a very marked dorsal flexure. 
The abdomen is elongated, the tail-fan enlarged, the 
exopoditic scales of the second antenne also enlarged, and 
the eyes are borne on elongated stalks. All these characters, 
which differentiate Paranaspides from the other Anas- 
pidacea, are correlated with the habits of the animal, which 
