34 

 13. Undinopsis similis, G. 0. Sars, n. sp. 



(PI. XXI). 



Specific Characters. Female. Very like the proceeding species in external 

 appearance, though perhaps somewhat more robust of form. Lateral projections 

 of last segment of metasome comparatively short, scarcely reaching beyond the 

 middle of the genital segment. Anterior antennae likewise shorter than in U. 

 Bradyi, not nearly attaining the length of the anterior division, otherwise of a 

 structure very similar to that of the said species. Posterior antennae with the 

 outer ramus distinctly longer than the inner. Inner ramus of 2nd to 4th pairs 

 of legs without any spinules on the hind face. 



Male resembling that of the type species ; the anterior antennae, however, 

 less slender, and with all the articulations well defined. Both legs of 5th pair 

 well developed, and having at the end of the 2nd joint inside a styliform appen- 

 dage (inner ramus), right leg considerably stronger than left, and terminating in 

 an incurved claw. 



Colour about as in U. Bradyi, though with less distinct pigmentation. 



Length of adult female 3.00 mm., of male 2.40 mm. 



Remarks. This form so very closely resembles the type species in its 

 external appearance, that it may easily be confounded with it, and, indeed, it 

 is only quite recently that I have been aware of its specific distinctness. On a 

 closer examination, however, several well-marked differences are found to exist 

 in both sexes, proving it to be in reality a well-defined species. Thus in the 

 female the lateral projections of the last segment of the metasome are far less 

 produced, and the anterior antennae comparatively shorter. In the male these 

 antennae are also less slender than in the male of U. Bradyi, differing, moreover, 

 in the fact that all the articulations are well defined, whereas in the type species 

 some of them are coalesced. Finally, the last pair of legs in the male exhibit a 

 very different appearance from those in U. Bradyi, the right leg, which in that 

 species is rudimentary, being here considerably stronger than the left,' both legs 

 having, moreover, a well-marked rudiment of an inner ramus that is wholly wanting 

 in the type species. 



Occurrence. I have found this form not unfrequently in the inner part 

 of the Stavanger Fjord, at Jelso and Sunde. Like the preceeding species, it 

 only occurred close to the ground, and was accordingly captured by the aid of 

 the dredge, the depth ranging from 50 to 100 fathoms. It is very probable, that 

 this form' also occurs in other places upon our coast; but having formerly con- 

 founded it with U. Bradyi, I am unable at present to state the localities with 

 certainty. 



