264 REPORT—1858. 
with a summary of the species belonging to the Decapoda found here, con- 
trasting this with the numbers found in Great Britain generally, and also 
with those found in Ireland. 
The exact habitat of several species recorded here is as yet a desideratum, 
although some of these are by no means rare as drift species; these are 
Portumnus variegatus, Corystes Cassivelaunus,extremely common; Gonoplax 
angulatus, drifted in at Portmarnock (supposed to inhabit mud banks near 
Knocknagin ; for this note Iam indebted to Charles Farran, M.D.) ; Aée- 
lecyclus heterodon (full-grown specimens), Portunus areuatus, Portunus 
corrugatus, Galathea nexa, Bernhardus Prideauxii, Palemon serratus, Pali- 
nurus vulgaris. 
The following species have as yet been noted only on the Dublin coast :— 
Crangon Allmanni (also Belfast, August 1858), Pandalus leptorhynchus, 
Iphimedia Eblane. 
The following hasnot occurred elsewhere inIreland:—Crangon trispinosus; 
and many species, as Crangon sculptus, C. fasciatus, Pirimela denticulata, 
are of extreme rarity elsewhere, : 
In Dublin Bay, as will be seen by reference to Table B, Appendix, have 
been recorded fifty-nine species of Decapoda out of the ninety-one positively 
recorded in Ireland. These represent thirty genera,—the genera wanting 
here being Maia, Pisa, Acheus (?), Polybius, Thia, Nika (?), Alpheus, 
Athanas—all genera of the south and west ; Munida, Gebia, Calocaris, Cal- 
lianassa, genera of deep sea or mud-burrowers, and Cynthilia, Macromysis, 
Vaunthompsonia, Iphinoe, and Cyrianassa, genera as yet but little under- 
stood and easily overlooked. Pasiphaé is the only genus which has not 
been met elsewhere in Ireland; its occurrence in Dublin is doubtful (vide 
Appendix, Table A). 
Of the thirty-two Irish species not recorded in Dublin and not belonging 
to the genera here noticed, Xantho rivulosa and tuberculata, Portunus ear- 
cinoides and marmoreus, Pinnotheres veterum, Hippolyte Mitchelli, Palemon 
Leachii, Mysis Griffithsii (?}), are probably western and southern. Inachus 
leptochirus, Crangon bispinosus, Bernhardus Forbesii, inhabitants of deep 
water, and Crangon spinosus, a northern species; Bernhardus levis and 
Acheus Cranchit have been reported to me, but I hesitate to insert them at 
present. 
As compared with the numbers given as British, it must be borne in mind 
that among the latter are included many whose specific value is doubtful; at 
the same time we could scarcely expect that all the northern or southern 
species which occur around the coast of Great Britain, should ever be found 
here. Of most of the species recorded here, I have procured specimens in 
ova, from many of whick I have succeeded in hatching the zoes ; these, should 
time permit, I would propose to notice in the concluding portion of my 
report, when I come to speak of the development of the group generally. 
Lists of the genera, families, and species are appended. 
