AN IOHTHYOBDELLID PARASITIC ON SAND WHITING. 5 
and lateral to it presents a shouldered appearance ; but the 
body is only slightly flattened. When a length of 7*5 mm. 
(Text-fig. 1) is reached the lateral development is quite pro- 
nounced, causing a more flattened form, and the suckers have 
assumed the ratio shown in the figure of an adult specimen, 
9 mm. (PL 1, fig. 5). 
Text-fig. 1. 
Outlines of specimens of A ustrobdella translucens which 
measure P5, 3, 4, 5’5 and 7‘5 mm. long. The figure showsthe 
change in shape during the growth of this marine leech. 
I give below a table to show the measurements at different 
stages of development : 
Length. 
15 mm. 
4*0 mm. 
7‘5 mm. 
9-0 mm. 
Breadth below 
Clitellum. 
T3 mm. 
‘52 mm. 
-135 mm. 
3 25 mm. 
Height. 
13 mm. 
'5 mm. 
‘7 mm. 
10 111 m. 
Diameter 
Oral Sucker. 
13 mm. 
‘30 mm. 
•55 mm. 
•8 X 5 mm. = 
•65 mm. 
Diameter 
Posterior, Sucker.; 
•20 mm. 
•41 mm. 
91 mm. 
1-75 X 11- 
142 mm. , 
The measurements given for the 9 mm. stage are from the 
specimen which is shown in PI. 1, fig. 5. The following 
additional .measurements are also from this specimen : 
