Bibliographical Notices, 371 



of which the results are emhodied in Paul Gaimard's 'Voyages de 

 la Commission du Nord en Scandinavie, Laponie,' &c. ; but although 

 several plates have been published containing drawings and analyses 

 of the animals collected, no text has hitherto appeared. This defi- 

 ciency, the reasons of which Dr. Kroyer promises to explain on a 

 subsequent occasion, he now intends to remedy to some extent ; and 

 the treatise before us must in some degree be looked upon as a 

 step in that direction. The descriptions, which in accuracy leave 

 nothing to be desired, are in Danish ; but the very full diagnoses, 

 as well as the explanations of the plates, are in Latin. To these 

 we can therefore refer, contenting ourselves with a few general re- 

 marks. 



In Milne-Edwards' s ' Histoire Naturelle des Crustaces ' only five 

 species of Mysidce are described, of which three belong to the northern 

 seas — viz. Mysis spinulosa, Leach, M. Chamceleon, Thompson, and 

 M . vulgaris, Thompson. The number of northern species is, however, 

 much greater, as Dr. Kroyer enumerates seven Scandinavian species, 

 amongst which the M. spinulosa, Leach, is probably not included. 

 Three of these seven species are exclusively Arctic, viz. M. oculata, 

 Fabr., M. arctica, Kr., and M. latitans, Kr. ; the others are found 

 along the shores of Norway, Sweden, and Denmark, from Throndhjem 

 to the Sound. M. Jlexuosa, Muller, besides, penetrates as far into 

 the Baltic as Gotland. M. inermis, Rathke, and M. cornuta, Kr., 

 reach into the Arctic seas, but not into the Baltic, whilst M. vulgaris, 

 Thompson, is principally found in the fjords of Jutland and in the 

 Sound. The M. oculata was first described by Fabricius in his 

 ' Fauna Grcenlandica,' and afterwards by Leach, as M. Fabricii. It 

 is the commonest species in the Arctic seas, and the principal food 

 of whales and sea-birds at different seasons. To this species tab. 8. 

 fig. 2 a-r, in Gaimard's 'Voyages,' &c, has reference. M. latitans, 

 Kr., is a new species, found together with the M. oculata, which it 

 much resembles. The M. latitans, is, however, smaller and more 

 slender. M. arctica seems to be a rare and very remarkable form, 

 having the dorsal shield very large, covering all the joints of the 

 cephalo thorax, and divided by a remarkable, deep transversal groove 

 into two parts ; the frontal rostrum is also unusually distinct, though 

 short. M. Jlexuosa, Muller (Prodromus Zoologise Danise, 1776), is 

 the species of Mysis which has been earliest described with sufficient 

 distinctness to be recognized ; and Midler's name must therefore 

 supersede the Thompsonian 31. Chamceleon. Dr. Kroyer leaves it 

 undecided whether Thompson's M. Leachii and Leach's M. spinulosa 

 also refer to this species. To M. Jlexuosa belong figs. 1, 2, & 3 on 

 tab. 9 in Gaimard's work. On page 44 in the ' Tidsskrift,' will be 

 found a table (in Latin) for the determination of the species of Mysis 

 mentioned in Dr. Kroyer's paper. 



The author next describes a new Cynthia from the Atlantic, which 

 he proposes to call inermis, and which is distinguished from C. armata, 

 M.-E., by the shortness of the frontal rostrum, and from C. Thomp- 

 sonii, M.-E., by a number of less conspicuous but not less significant 

 marks. Another species shows sufficient peculiarity of structure to 



25* 



