440 Deep-sea Trawling off the S.W. Coast of Ireland : 
Echinus microstoma, Wyv. Thoms. 
(PI. XIX. fig.'1.) 
There is certainly among these Echini a species distinct 
from EH. acutus or E. esculentus; it has a bright red test and 
that test is depressed and thin. It is a little doubtful how 
much stress should be laid on colour and particularly red 
colour in Echinoderms; depressed tests may certainly be seen 
in specimens of species which are not always characterized by 
their possession; but the thinness of these tests is quite well 
marked. ‘The specific name calls attention to the characters of 
the mouth ; but smallness and largeness are relative terms, and 
I give, therefore, some measurements which Wyville Thomson 
omitted to add to his description. I have also thought it 
necessary to refigure the species, for the representations offered 
by Thomson are by no means good, and the differences between 
E.. microstoma and LE, elegans are hardly at all indicated. A 
reference to figs. 8 and 9, pl. Ixvi. of Thomson’s memoir 
and to fig. 3, Pl. XIX. of the present paper will show the 
difference in the form of the C-shaped spicules of these two 
species. 
Diam. of test. Height of test. Diam. of mouth. Diam. of anus. 
millim. millim. millim. millim. 
50 Dee 12 
(50) (24) (10) 
47 20 13 5 
(42:5) (27-6) (10°6) 
43 195 Mes 
(45:3) (26:7) (11:6) 
40 21 105 45 
(52-5) (26:2) (11-2) 
Echinus esculentus, L. 
Two specimens, one from 50-66 fath., the other from 110 
fath. 
Both examples are somewhat compressed instead of being 
globose, and tend towards the “ marked variety with a tall, 
narrow test” spoken of by Sir Wyville Thomson (¢. c. 
p. 744). The lowest recorded depth for this species that I 
can find is 80 fath.; Prof. Agassiz gives no specific informa- 
tion on this point in his ‘ Challenger’ Report. 
* As no measurements have yet been given of this species, I give the 
absolute values; the percentage values, which are much more valuable 
for the purposes of comparison, are added in brackets. There is no better 
method for showing the range of variation. For the purposes of comparison 
I give the following percentage measurements of a rather young E. 
acutus, the diameter of which is 51 millim,:—height 58:8, mouth 35°38, 
anus 18. 
a fw 
