

Pee hore aye se euphyBopoda «0° e's ics Kae ae ¢ 
_ _ The specimens from the vicinity of Point Barrow, Alaska, collected by Mur- 
doch in 1882 were all females and measured from 1 to 2} cm. to end of telson. 
- The great majority of the 50 specimens from July 21, carried almost ripe eggs 
(except the youngest individuals), but none of the 15 specimens (1-12 em. long), 
from July 10 had any eggs. Murdoch (1885) notes, that in 1882 they were first 
observed on July 8, but the next year ten days later;! and these early specimens 
were probably less than 1 cm. long, and the brood of the year. Armature and 
shape of telson are as in the Canadian Arctic Expedition specimens of corre- 
sponding sizes. | 
The specimens from Martin point, Alaska, measured from 83% to 18 mm. 
to end of telson; I give here (text figures 1b, c) outlines of the shape of telson of 
the two extremes of size of these animals. The armature of spines on telson of 
the 18 mm. long specimen was as in the 12 mm. long specimen from Teller, 
Alaska (see above), while its cercopods were 10 mm. long. Only three of the 40 
specimens were less than 11 mm. in length; the others had shape and armature 
of telson as in the 18 mm. long specimen or as in the two specimens from Teller. 
When seen in the water the carapace of the living animals was spotted light 
and dark brown (coloured like the mud-bottom of the lagoon-pond they occurred 
- in), with the paired eyes blue, lined with purple. Head and tail coloured like 
carapace, but certain places (“‘snout’’ and underside of free tail end) with rose- 
purple. Cercopods brown. Inner side of carapace rose-brown. Foliaceous legs 
brown-green with pale appendages, the 11th pair of legs (female) darker green 
and with rose, big eggs. Telson pale greenish-blue, with base of cercopods dark. 
‘These Lepidurus were swimming around very actively in the shallow lagoon-pond, 
, making by movements of the foliaceous legs their characteristic long, winding 
furrows in the mud surface; or burying themselves in the latter, so that their 
trails were more obscure, with an animal at one end of each. Their food con- 
sisted of the still smaller invertebrates (Daphnia pulex, Copepods, midge-larvae, 
etc.) present in great numbers here. As I collected practically all the Lepidurus 
I saw in this pond their size indicates that they all belong to the brood of the 
year (1914), and thus were almost two months old. 
~The specimens from Bernard harbour July 3, 1916, measured only from 3 
to 10 mm. in length, with cercopods from 14 to 5 mm. long. As mentioned 
p. 5 these are the youngest individuals secured during the expedition, and I 
give here (text figure 1f) an outline (dorsal view) of telson and its armature of 
the smallest specimen. A comparison with text figures 1b, g, will show that the 
outline of telson is more rectangular than triangular, and runs out into three 
long spines and a very short one, while the older stages (more than } cm. long) ~ 
have only two larger spines here, between which (with specimens more than | cm. 
long) are found a few smaller spines. From the many American specimens I 
have examined this seems to be a constant and characteristic armature of the 
telson even in very big (up to 3 cm. long) individuals, while the row of tiny 
spines on the middle of the dorsal side of telson vary in numbers from two to’ 
four, as also the number of still smaller spines? between the terminal end of — 
telson and the cercopods. In individuals less than 3 mm. long the shape of the 
telson is also more rectangular than triangular, and according to Sars (1896) - 
and Brehm (1911)? ends in only two well-defined spines (points). From the 
text figures la, b, c, g, h, and Olofsson’s account (1918, p. 384-86, figs. 
18-19), it will also be seen how the outline of telson from rectangular 
becomes triangular, and in the older individuals almost spatulate, though 
they do not reach the maximum development in the latter direction (which 
seems to be accompanied by a reduction in length of the spines) shown 
by specimens from Norway (Sars, 1896, Tab. XII).4 In color even the smallest 

1 From the narrative of the expedition, it appears that. the summer came later in 1883 than in 1882. 
‘ 2 These spines seem to be absent with individuals less than about 4 mm. long. 
3 See text figures 1d, e (copies). 
4 Data about the growth of the cercopods are given by Olofsson (1918). 
