COLLECTED BY CAPTAIN TOYNBEE. 17") 
seem to show that it is in reality more nearly allied to the typical Calanl. More- 
over, in certain Calani (as, for instance, in C. elongatus) the anterior antenna bears 
here and there long setae, almost as in Euchceta. C. latus seems therefore, to me, to 
form an interesting link between the two above-named genera. The Galanidae, many 
as are the species which yet remain to be discovered, present us with a very perfect 
gradation of forms; and indeed the whole tribe of Cyclopoidea offers in this respect 
a marked contrast to the Cyproidea. This latter group is at present poor both in 
genera and in existing species, and it is in many respects very aberrant. The Cyclo- 
poidea, on the contrary, contain an immense number of species, which, as I have just 
remarked, form a somewhat complete series, or rather network. In this great family, 
then, it would seem that most of the types are still existing, that there has as yet been 
no very great amount of extinction, and that the type is not, geologically speaking, very 
ancient. The nature of the body is certainly not favourable for preservation, and nega- 
tive evidence is of very little value in geology; still it is worthy of remark that the 
group, now so numerous, has not as yet any known extinct representatives, though, from 
the great differences between some of the existing species, we may safely infer that the 
group is of considerable antiquity. The Cyproidea, on the contrary, are known to have 
existed as early as the Silurian period. They are therefore a very ancient type ; a great 
proportion of the known species are fossil ; and as the soft parts are never preserved, 
we cannot expect to recognize among them more than a few of the links which must 
have connected the different genera with one another, and the whole group with what we 
now consider the more normal Crustacea. 
Diaptomus ? abdominalis, again, is obviously a link between Diaptomus and the species 
placed by Dana in his genus Hemicalmws and the ordinary Calani,— possessing, as it does, 
the second maxilke and second antennae of the latter, with the geniculating anterior 
antennas and abnormal posterior legs which are characteristic of the former. Indeed, 
unless it is admitted to constitute such a link, it must be considered as the type of a 
new genus. I did not, however, adopt this view in 1856, nor am I disposed to do so 
now. Such a course, if followed in other similar cases, would lead to an immense and 
at present unnecessary multiplication of genera. This species, moreover, even - if called 
by any other name," would be just as much intermediate between the above-named genera 
as before. In order, however, to retain this species in the genus Diaptomus, it will be 
necessary to modify the generic character given by Dana, in so far as concerns the pos- 
terior legs of the females. 
The structure of the anterior antennas, again, is intermediate between that of Calm us 
and that of Fontella. The right antenna differs slightly from the left, and may perhaps 
be rightly described as geniculating ; but the prehensile power must be very small. 
The second pair of antennas have the two branches equal. The mandibles and first 
pan of maxillas resemble those of Calanus brevicornis (Trans. Ent. Soc. n. s. vol iv pi 3. 
I 3 & 4). The second pair of maxilla and maxillipeds are as in Calams; the latter 
has the terminal segments elongated. Mrs. Toynbee's collection included no mature 
males. The fifth pair of legs in the females (I c. pi. 10. t 6.) differ slightly from those 
originally figured by me. The present specimens, however, were rather smaller, and 
2 A 
