jQ CRUSTACEA MALACOSTRACA. II. 



in the shape and equipment of the molar processes sucli differences as those judged b\- vSars to be of 

 generic value. The result is that the value of the shape of tlie molar processes as generic characters 

 is lessened both from a scientific and a practical standpoint. 



Though the descriptions of species published b>' (t. (). Sars, Norman and Stebbing on the whole 

 must be considered good, some of the characters in the family Tanaidse used by these authors are 

 scarcely sufficiently sharp, as a larger number of species have been discovered and it can be proved 

 than hundreds of species are still undiscovered. While drawing the figures I found it necessary to 

 use the ocular micrometer very much in order to figure as exactly as possible not only the relative 

 length of the segments and of the joints of all appendages, but besides the exact proportion between 

 length and breadth or depth of the joints of the chelipeds, the antennulae and the peduncles of the 

 uropods. Very frequently it is stated in the following pages that a joint is somewhat less than twice 

 as long as deep or more than half as long again as another joint, etc., and in all such and several 

 other cases the statements are founded upon measurements. As some slight individual variation exists 

 and in some cases may be more pronounced, the proportions stated may sometimes be only approxim- 

 ative, but in spite of such variation I thought it better to give statements based on measurements 

 than such founded on measuring by the eye. 



Especially the relative length and l)readth or depth of some of the joints of the chelipeds 

 afford excellent specific cliaracters, but care must be taken that the joints are seen exactly from the 

 side, as an oblique position of a joint produces an erroneous impression as to the relative dimensions. 

 The shape and length of all or of the three proximal joints of the antennulae are also valuable. The 

 processes on the ventral side of the abdominal segments in Cryptocopc ]^d n'rigii G.O.S. and C.arclo- 

 pliylax Norm. & Stebb. were pointed out in the literature, but in many species of Lcptogiiatliia the 

 presence or absence of ventral tubercles or of a peculiar process afford valuable characters. But it is 

 scarcely necessary to say more on these topics, as the perusal of a few descriptions of species belonging 

 to different genera ma}- elucidate the methods applied. 



Fam. I. Apseudidae. 



This family comprises eight genera, but only two are represented in tlic collection. 



ApseudeS Leach. 

 In the literature twenty-eight species have been established. The "lugolf captured three 

 .species, one of which is new; furthermore two specie.s, both new, have been secured by the "Thor". 



I. Apseudes spinosus M. Sars. 

 1859. Rhoea sp/iiosa M. Sars, Forh. Vid. Selsk. Christiania for 1858, p. 30. 



1886. Apsnidrs spinosus Norman & .Stebbing, Transact. Zool. Soc. London, \'ol. XII, Pt. I\', p. 8^, 



PI. XVII, fig. I. 

 ! 1896. — — ti. (). Sars, Account Crust. Norway, Vol. II, p. 7, Pis. I— II. 



