388 Mr. Gwyn Jeffreys on Dredging among the Hebrides. 
second is Zetlandic, Scandinavian, and North American, although 
it has also been procured in the Orkneys and on the Aberdeen- 
shire coast ; the third is Zetlandic, and the fourth Zetlandic also 
and Norwegian. It must be borne in mind, as regards the 
extent of geographical distribution, that the southern extremity 
of the Shetland Isles is distant about 200 miles from the north- 
ern extremity of the Hebrides “as the fish swims.” Besides 
the four last-named species, the following seem to reach their 
most southern limit in the Hebrides :—Luma elliptica, Leda 
pygmea, and Trochus Grenlandicus. Leda pygmea has indeed 
been dredged on the coast of Antrim; but I am now inclined to 
regard the specimens thus obtained as quaternary fossils. 
Tethea cranium (a sponge not before known south of Shetland) 
occurred in tolerable numbers on the Ross-shire side of the 
Minch. Species of Mollusca, inhabiting the Hebridean seas, 
which are in the main northern (although they have been found 
somewhat further south, and some of them occasionally even in 
the Mediterranean), are—Argiope cistellula, Pecten striatus, 
Mytilus phaseolinus, Modiolaria nigra, Crenella decussata, Nucula 
tenuis, Leda minuta, Arca pectunculoides, Montacuta ferruginosa, 
Cyamium minutum, Cardium minimum, Cyprina Islandica, Astarte 
compressa, Tellina pusilla, Scrobicularia nitida, Thracia convexa, 
Mya arenaria, M. truncata, Chiton Hanleyi, C. albus, C. ruber, 
C.marmoreus, Tectura testudinalis, T. fulva, Propilidium ancyloides, 
Puncturella Noachina, Emarginula crassa, Scissurella crispata, 
Trochus helicinus, Lacuna divaricata, L. puteolus, L. pallidula, 
Rissoa albella, Jeffreysia diaphana, J. opalina, Odostomia minima, 
O. albella, O. imsculpta, O. diaphana, Velutina plicatilis, V. 
levigata, Trichotropis borealis, Purpura lapillus, Buccinum unda- 
tum, Trophon Barvicensis, T. truncatus or Banffius, Fusus antt- 
quus, F. gracilis, Nassa incrassata, Mangelia turricula, Defrancia 
scabra, Cylichna nitidula, Amphisphyra hyalina, Philine scabra, 
P. pruinosa, and P. quadrata. 
For certain species, which are almost peculiar to the Hebrides, 
I am not aware that any locality has been recorded between that 
district and the Mediterranean. Such are Aainus ferruginosus, 
Poromya granulata, Neera abbreviata, N. costellata, and Cylichna 
acuminata. The first three of these were described by the late 
Professor Edward Forbes, in the Report to the Association in 
1843 on Aigean Invertebrata. Another Hebridean species 
(Nucula sulcata) is not found southwards nearer than the coast 
of Spain. 
Some of our most conspicuous and prized shells, that are also 
of a northern type, are wanting in the Hebrides. Saaicava 
Norvegica, Natica Grenlandica, Buccinum Humphreysianum, 
Buccinopsis Dalei, Fusus Norvegicus, F. Turtoni, and F. Berni- 
