CHAP. II. ] THE CRUISES OF THE ‘ PORCUPINE,’ [leh 
marked differences as distinct species, after having 
gone over some thousands of them—some brought 
up in nearly every haul of the dredge from F'roe to 
Gibraitar—I am inclined to suspect that they may 
be all varieties of Hehinus flemingit. I have already 
alluded to the countless myriads in which the 
small form of FL. norvegicus, D. and K., 15 mm. in 
diameter, swarms on the ‘Haaf’ fishing banks. 
These little urchins are mature so far as the develop- 
ment of their generative products is concerned ; and 
I suspect from the abundance of three sizes, that they 
attain their full size in two years and a half or three 
years ; but in colouring, in sculpture, and in the 
form of the pedicellarize, | do not see any character to 
distinguish them from a form four times the size, 
common in deep water off the coast of Ireland; nor, 
again, can I distinguish these last by any definite 
character which one would regard as of specific value 
from the shallow-water form of Echinus flemingii, as 
large as the ordinary varieties of L. sphera. 
The Shetland variety of Hquus caballus is certainly 
not more than one-fourth the size of an ordinary 
London dray-horse, and I do not know that there is 
any good reason why there should not be a pony 
form of an urchin as well as of a horse. 
Professor Alexander Agassiz’ has discovered that 
the Florida species of HKehinocyamus is nothing more 
than the young of a common Florida clypeastroid, 
Stolonoclypus prostratus, Ac., and he suggests the 
possibility of our Lehinocyamus angulosus, LESKE, 
being one of these stunted ‘pony’ varieties, or un- 
developed young, either of the American Stolono- 
1 Bulletin of the Museum of Comparative Zoology, No. 9, p. 291. 
