744 
PROFESSOR WYVILLE THOMSON ON THE ECHINOIDEA OF THE 
of colour to the upper surface. The spines are whitish, and the ambulacral part grey 
tinged with purple . , A large mutilated specimen of this species, and a smaller one 
nearly perfect, were dredged by Mr. Gwyn Jeffreys off the coast of Portugal. There 
was a fragment of the test taken by the dredge off Rockall, and some spines which 
must be referred to it were sifted out of the mud brought up by the dredge in the Bay 
of Biscay. 
III. 
Received April 9, 1874. 
Family 3. Echinidaj. 
Genus Echinus , Link. 
1. Echinus melo , Lamarck. 
Two specimens were dredged off the coast of Portugal in shallow water. 
2. Echinus Flemingii , Ball. (Plate LXVIII. fig. 14.) 
The large typical form of this species was met with in deep water off the Shetlands, but 
not in large numbers. 
3. Echinus rarispina , G. O. Sars. 
4. Echinus elegans, Von Duben and Koren. (Plate LXVIII. figs. 11-13.) 
5. Echinus norvegicus, Von Duben and Koren. 
The last four are critical species ; and although the extreme forms are very dissimilar, 
in a large series there are so many intermediate links that it is difficult to tell where the 
one begins and the other ends. It is possible that when our information is more com- 
plete all these may come to be regarded as varieties, and may be grouped together under 
Lamarck’s name, Echinus acutus. 
6. Echinus microstoma, nov. sp. (Plate LXVIII. figs. 1-10.) 
Although I have great hesitation in proposing an addition to the genus Echinus, I 
feel compelled to separate, in the meantime, this very distinct form with a thin depressed 
test, a remarkably large apical system and periproct, a small peristome with the margin 
curved inwards and a uniform salmon-colour. Echinus microstoma is very abundant 
at depths between 150 and 400 fathoms off the western coasts of Scotland and Ireland. 
7. Echinus esculentus, L. 
A marked variety with a tall narrow test occurred in deep water off the Faeroes. 
