occurring on the Xorwetjian Coasts. 3^jl 



the head, eyes, antennae, and abdomen, and partly also in the 

 outer lamella of the maxillipedes, which is operculitonn ; but 

 here there are pal{)i, which are wanting in the ilyperiche. On 

 the whole, tiic ])arts ot" the mouth in this animal are peculiar, 

 and a])pear as it' intended for sucking. In some respects it 

 approaches the Orchestida?, but has also much in common with 

 the genera Opis and Anonyx among the Gammaridie in the 

 structure of its antennse and feet. 



Tribe III. Gammarid^ : — 



Family I. Orchestidae. — Xone of the characters which are 

 proposed for this family belong to it exclusively, or are con- 

 stant in all its forms. By the long superior antenna? and the 

 well-developed claw on the palpi of the maxillipedes in Allor- 

 chestittj this family approaches the Ganmiarida?, from which, 

 again, it is not clearly separated by the want of mandibular 

 palpi, as these are also wanting, for example, in the genus 

 Dejcamine. Acanthonotus and Stegocephalus possess a short 

 maxillary palpus like that of Allorclieatia. Again, the pecu- 

 liar form of the abdomen is not exclusively characterLstic of 

 this family, as it also occurs in several genera of the family 

 Corophidaj. The two genera of this family which occur on 

 our coasts differ from the other Amphipoda, however, by the 

 series of spines on the mandibles. This is formed by long, 

 thick, but flexible, and strongly ciliated hairs, whilst those of 

 all other Amphipoda examined by me consist of simj)le denti- 

 culated spines, or of spines divided at the apex. In the struc- 

 ture of the inner lamella of the first i)air of maxillaj (which is 

 long, narrow, and furnished at the end with two long, ciliated 

 hairs) the family much resembles the genera ^I/io/?_yj; and Opis^ 

 which it also resembles in having the ovigerous lamella? longer 

 and much narrower than the rcsj)iratory lamella?, and at the 

 same time furnished with long, Ijut not approximated, hairs. 

 In both our genera of this family there is in the males the 

 peculiar double armature of teeth, which is wanting in the 

 females. In AUorche^ia Nilsonii this is particularly distinct 

 on the mandibles and first pair of maxilli\3. 



Family 2. Gammaridae. — For this family it is still more dif- 

 ficidt to lay do\\ni definite limits. Neither ]\Iilne-Edwards's 

 statement that his Creirttiius nunrheusesj which nearly coin- 

 cide with Dana's family Corojihida?, are distinguished from 

 the Crevettines sauteunes by their less compressed body and 

 their small epimera, and by the three hinder pairs of abdo- 

 minal legs being furnished with " lames natatoires," and 

 not formed as a jumping-apparatus, nor Dana's statement 

 that his Corophida? have " pedes ]»arlim lateraliter porrecti," 



