292 A HISTORY OF RECENT CRUSTACEA 
eight families, together containing twenty-five or twenty- 
six well-defined genera, and about a hundred and eighteen 
satisfactorily determined species. In certain localities the 
extreme abundance of some of these supplies a welcome 
food to shoals of herring. In size and number of indivi- 
duals the Aretic species appear to excel all others. It is 
probable that many forms still remain to be discovered, 
since up to 1876 a single species obscurely described from 
the Black Sea was the sole representative of the sub-order 
in the area of the Mediterranean, where in the winter of 
1876 Professor Sars found no less than twenty-three 
species, of which fourteen were new to science. Before 
1859 none were known from the waters of the Clyde, and 
in these Mr. David Robertson, of Cumbrae, has since 
found fifteen species. 
Among the curiosities of scientific literature are the 
disputes which have occurred actually within the last fifty 
years, as to whether the Cumacea did or did not possess 
organs of vision, and as to whether they were or were not 
merely larval forms. The well-known and diligent ob- 
server, Colonel Montagu, at the beginning of the century 
found in South Deven a species which in fact possesses 
sight, but not unnaturally Montagu did not attempt to 
discover the creature’s eye, because he was under the 
impression, though an erroneous one, that his solitary 
specimen had lost its head. Kréyer, many years later, 
happening to meet with various species which are in truth 
blind, formed the opinion that all the species were so, and 
that eyes had been attributed to some of them under an 
illusion. Harry Goodsir, a Scotch naturalist, m 1843 
published the remarkable statement that the eyes are 
‘pedunculated but sessile.” He lost his life not long 
afterwards in Franklin’s Arctic expedition, and left his 
opinion to be for many years doubted, denied, or sup- 
ported, without its being in his power to explain that 
what he obviously intended to print was that the eyes 
were not pedunculated but sessile. It is probable that 
Kroyer was completely mystified by the misprint. ‘Good- 
sir,’ he says, ‘thought that eyes must be found in the 
