116 DUBLIN NATUaAL HISTOKY SOCIETY. 



pleon (abdomen). I cannot satisfy myself that in the type Crustacea of 

 twenty-one rings we have more than two primary divisions, viz., four- 

 teen anterior rings (cephalo- thorax), seven posterior rings (abdomen). In 

 some genera and groups we find (as Amphipoda) the first of these split 

 up secondarily into two parts, and here it doubtless is convenient to name 

 each of the parts. Used in this subordinate sense, the terms head, cepha- 

 lon (or what I conceive means the same thing), carapace (as correctly 

 used), and pereion, or thorax, may be used. Abdomen and pleon are 

 confessedly identical — the only objection to the former term being, that 

 it has been used to express an organ among the Yertebrata, an objection 

 which, perhaps, after all does not signify much. The appendages of the 

 segments, however, much need distinctive names, and there can be no 

 objection to those suggested in the Report alluded to. Telson, in the same 

 manner, appears to be an organ which is constant in its relations, and a 

 most important one, specifically speaking, among the Isopoda. 



I would suggest the following alterations in the sequence of the 

 families of Oniscoidea as given in the Analysis : — 



Tylidse, ActaecidaB, PorceUionidae, Oniscidae, Philoscidae (Philoscia, 

 Scyphax), Philougridae, Titanethidae (Titanethes, Styloniscus,Ligidium), 

 Ligidae. 



DESCRIPTION OF PLATE XXIII. 



Fig. 1. Philougria ripa/ria magnified : — \h, posterior pleopod; 1/, mi- 

 croscopic appearance of integument 



rig. 2. Phil, vivida : — 2 d, posterior pleopod ; 2 c, inferior view of an- 

 tennae ; 1 e and 2 e, internal antenna ; 2/, integument. 



Fig. 3. FMl. rosea : — 3 b, telson and posterior pleopod ; 3 c, inferior view 

 of head; 3/, integument. 



Fig. 4. Philoscia Couchii : — 4 h, telson and posterior pleopod ; 4 d, pos- 

 terior pleopod. 



The President declared the following gentlemen duly elected : — 



HoNOEAKY Member. — Charles Spence Bate, F. L. S., Plymouth. 

 CoKKESPONDiNG Member. — Jamcs Martin, M. D., Portlaw. 

 Ordinary Members. — John M'llwaine, Esq., Dublin; M. Weld 

 O'Connor, Esq., Dublin; Robert Samuel Reeves, Esq., Dublin. 



The Meeting then adjourned to the month of June. 



FRIDAY EVENING, JUNE 4, 1858. 

 Charles P. Croker, M. D., M. R. I. A., Vice-President, in the Chair. 

 The previous Minutes having been read and signed, — 



