112 



71. Parathalestris harpacticoides (Glaus). 



(PI. LXVII). 

 TJialestris harpactoides, Claus, Die freilebenden Copepoden, p. 133, PI. XIX, figs. 2 11. 



Specific Characters. Female. Very like the preceding species, but of 

 smaller size and on the whole less strongly built. Cephalic segment comparatively 

 larger, considerably exceeding in length the 4 succeeding segments combined; 

 rostrum somewhat more prominent. Urosome exceeding half the length of the 

 anterior division and having the segments more sharply marked off from each 

 other, all, except the last provided on each side with a very conspicuous oblique 

 row of spinules. Caudal rami about as in P. Clausi. Anterior antennae com- 

 paratively more slender, with the distal part exceeding half the length of the 

 proximal one. Posterior maxillipeds far less powerful, with the hand oblong oval 

 in form and the dactylus more slender. 1st pair of legs of a structure very 

 similar to that in P. Clausi, though having the outer ramus comparatively nar- 

 rower and scarcely shorter than the inner. Last pair of legs with the distal joint 

 less broad, oblong oval in form, inner expansion of proximal joint likewise nar- 

 rower and extending scarcely as far as the distal joint; marginal setse of both 

 joints more elongated than in P. Clausi. 



Male exhibiting similar differences from the female to those in P. Clausi. 

 Last pair of legs, however, conspicuously differing in shape from those in the 

 male of that species, the distal joint being much narrower and scarcely at all di- 

 lated at the base, inner expansion of proximal joint very slight, with 3 marginal 

 setse, none of which are spiniform, innermost seta the shortest. 



Colour generally dark olivaceous. 



Length of adult female 0.73 mm. 



Remarks. As stated above, this form is closely allied to P. Clausi, ex- 

 hibiting a very similar structure of the 1st pair of legs. On a closer comparison, 

 however, some well-marked differences in the structural details are found to exist, 

 proving these two forms to be in reality specifically distinct, though unquestionably 

 congeneric. An easily recognizable external character is also found in the oblique 

 rows of spinules on the sides of the caudal segments, of which scarcely any trace 

 is found in P. Clausi. 



Occurrence. This is also a rather common form, being found along the 

 whole south and west coasts of Norway in the littoral and sub-littoral regions 

 among algae. In the upper part of the Christiania Fjord this form is by far the 

 most frequent. 



Distribution. Heligoland (Glaus), British Isles (Brady), coast of Bohuslan 

 (Coll. Cleve). 



