DUBLIN NATURAL HISTORY SOCIETY. 81 



The species referred to this genus are as follow : — 



Crangon vulgaris (Fabr.). 

 „ fasciatus (Risso). 

 „ spinosus (Leach). 

 „ sculp tus (Bell). 

 „ trispinosus (Hailstone). 



Crangon bispinosus (Hailstone). 

 ,, boreas (Phipps). 

 loricatus (Risso). 

 munitus (Band). 

 nanus (Kroger). 



Of which the first six are recorded as Irish, the first five having occurred 

 in the eastern or Dublin district ; to these must be added the species to 

 be now described — C. Allmanni (mihi). 



Leach and Risso divided the species then known into three genera — 

 Crangon, Pontophilus, and .ZEgeon ; of these the two latter have been, 

 by modern systematists, rejected as founded on insufficient characters, 

 and, therefore, not natural groups. There appear to be good grounds 

 for this opinion as regards JEgeon ; but it is probable that further study 

 of the homologies of those already known will lead to the re-establish- 

 ment of Leach's genus, Pontophilus. 



This genus was founded for those species in which the second pair 

 of legs were much shorter than the first, the foot-jaws having their ter- 

 minal joints long and slender, and the carapace covered with spinous 

 lines. Of these characters the second is found to be inconstant; the first 

 liable to confusion; but the third will, I am led to believe, be found 

 constant, although in some species these spinous lines are reduced in 

 number, and even replaced either by single spines, as in C. trispinosus , 

 or rows of notches, as in C. bispinosus. This division includes C. spi- 

 nosus, C. loricatus, C. sculptus, C. nanus (?), C. trispinosus (each row of 

 spines reduced to a single spine, those of branchial regions obsolete), 

 C. bispinosus, C. munitus. 



In Crangon proper, the second pair of legs equal to the first and 

 third ; the foot-jaws have their terminal joints somewhat shortened, 

 and we find one median spine on gastric region, and the lateral spines, 

 when present, inserted on the branchial region. Under this section are 

 arranged C. vulgaris, C. fasciatus, C. boreas (? ), and the new species, 

 C. Allmanni. For the present it is, probably, best to unite these two 

 groups, as Bell and M. Edwards have done, into one group, under the 

 name of Crangon. 



Crangon Allmanni 



C. Crangone vulgari affinis. Rostrum frontale brevie. Carapax 

 laevis, spinis tribus armatus, una brevissima regione gastrica mediana, 

 duae regionibus branchialibus insitae. Abdominis articulus sextus supra, 

 canaliculars, ultimus supra- sulcatus, dentibus binis utrinque armatus, 

 infra dentibus minutis praetextus. Pedum par primum subcheliforme, 

 brachium lseve et inerme. Maribus spina sternale brevissima, faeminis 

 obsoleta. Colore albus-caerulescens runs et aureis punctis maculatus. 



Habitat : "Zonam corallinam Maris Hibernici juxta ' Bray,' comitat : 

 'Wicklow.' Longit, uncise tres." 



VOL. IV. m 



