OF THE ENGLISH LAKE DISTJIICT. 
429 
It is evident that"., i£ L. grimaldii be tlie parent form, those races which 
approach it most nearly in shape of head and in other respects may be regarded 
as most nearly related, and consequently more recently sepai-ated from it. 
It is therefore of some interest to appl}' Ekman's system of measurement 
to races other than those of the Baltic region, and to see if by that means 
any clue to their age may be found. 
Fig. 2. 
Limnocalanus macnirus from Ennerdale, showing- method of measurement. 
A. Head-leu"th. B. Head-height. C. Crown-level. 
Table 6. — Measurements of Limnocalanus macnirus and L, grimaldii. 
Figures marlied * are taken from Ekman, 1914. 
Length. 
Furcal 
rami. 
Per cent. 
of body. 
Head- 
length. 
A. 
Head- 
height. 
B. 
Crown- 
level. 
A &B. 
Ennerdale 
2 
2a8 
206 
13-1 
14 
•29 
167 
-26 
131 
Sweden — Malaren 
2 
6 
2-34 
2-3 
16 
16 
•32 
126 
-16 
110 
„ Insjcin 
2 
2-1 
167 
■33 
137 
-|-4^4 
141^4 
U.S.A.— C4reen Lake .... 
2 
6 
2-28 
2-24 
14 
13-8 
■32 
134 
-1L5 
122^5 
„ Lake Erie 
2 
2-86 
27 
13-3 
13-3 
•37 
140 
-17 
123 
„ Lake Cauandaigii 
2-58 
2-51 
15 
]5 
•37 
•35 
136 
141 
-16 
-]3 
119 
128 
Caspian Sea 
2 
2-59 
15-8 
- 
90* 
-25* 
65* 
