338 Rev. T. E.. R. Stebbing 07i Amjihi'^jodous Crustaceans. 



discrepancy, the figure of A Uorchestes imhricatus shows the 

 telson divided. Specimens, moreover, from Torbay of a species 

 in other respects agreeing with ^//orc7iesfesiVi7s5on{ undoubtedly 

 have a divided telson. There is, indeed, a suspicious similarity 

 between the figures in the Museum Catalogue of Allorchestes 

 Nilssoni and Hyale pontica ; but whether these two are iden- 

 tical or not, it is pretty clear that Axel Boeck was right in 

 reducing the three genera iWcea, Allorchestes^ and Hyale to 

 one, the name Hyale being retained in right of priority. 



But if Axel Boeck is right in uniting the genera, he is un- 

 doubtedly wrong in confounding the two species Allorchestes 

 Nilssoni and Nicea Luhhochiana. The two are well discrimi- 

 nated in Mr. Spence Bate's Catalogue, to which Boeck him- 

 self refers. The Catalogue, however, describes only the male 

 of Allorchestes Nilssoni ^ and only the female or young oiNicea 

 Luhhockiana ; this is the case also with the subsequent work 

 entitled ' British Sessile-eyed Crustacea.' 



Both of the species, which should now be called respectively 

 Hyale Nilssoni and Hyale Luhhochiana^ seem to have an affec- 

 tion for tufts of PolysiphonicB and other finely branched weeds ; 

 the young forms especially may be taken from these tufts in 

 great numbers. Both old and young of H. Nilssoni are very 

 agile, and have the faculty, not apparently shared by their 

 neighbours, of rising on their feet and springing away in a 

 very abrupt manner. Well-grown specimens may be taken 

 in a state of suspended animation, rolled up in the green weeds 

 [Entei'omorjjhce) which coat the rocks at high-water mark. 

 The adult male in both species is distinguished chiefly by his 

 superior size generally, and by the largeness of the second 

 gnathopods in particular. In the young the two pairs of gna- 

 thopods are closely alike and nearly of the same size, the second 

 pair having in this respect a little the advantage. This obser- 

 vation applies to the females up to an age when they are already 

 prolific, at any rate in the case of H. Nilssoni^ though subse- 

 quently the females of that species have gnathopods agreeing 

 in shape with those of the full-grown male. The second gna- 

 thopods are then much larger than the first, with hands about 

 two fifths of the size of the bulky rounded claspers carried by 

 the male. 



The two species are so similar in general appearance, that 

 it may be convenient to notice those points in which they 

 more or less decidedly differ. In Hyale Nilssoni, by the 

 extent of the flagellum, the lower antennie are considerably 

 longer than the upper. The lower antennae often have the last 

 joint of the peduncle ornamented beneath by three rows of 

 cilia, Avhich are not to be found in the corresponding portion 



