studies on marine Ostracods 44^ 



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r shorter than thv antcrioi' edge ot tliis joint. Ventrally this bristle always has at the middle 

 numerous long, stiff secondary bristles, some of which are arranged in pairs; distally it has short, 

 fine hairs. In addition this joint has disto-laterally a bristle that is usually short and weak, with 

 short, fine hairs. The third joint has along its anterior edge a series of five or six bristles (cf. also 

 A. ahyssicola, p. 536 of this treatise), of which the proximal one and the distal one are in most 

 cases of about the same length as the bristle on the anterior edge of the second joint, the others 

 being somewhat shorter. (On account of this only the approximate length of the anterior bristle 

 on the second joint is given in the following descriptions of species.) All these bristles are rather 

 powerful and point more or less forwards and are bent more or less upwards. The proximal 

 one (= bristle no. 1) has about the same equipment as the anterior bristle on the second joint; 

 most, sometimes all, of the remaining bristles are furnished at the middle with a greater or less 

 number of more or less long and stiff ventral secondary bristles and have short, fine hairs distally; 

 the one or more that remain have short hairs but no long secondary bristles. The ecpiipment 

 of these bristles was, in the species investigated by me, fairly constant within the species. On the 

 short posterior edge of this joint there is only one exceedingly short and weak bristle. On the 

 short anterior edge of the fourth joint there is also only one bristle, which is of about the same 

 length and strength as the distal bristles on the anterior edge of the third joint and always has 

 short, fine hairs distally. Postero -distally on the same joint there issue two rather weak bristles 

 with fine, short hairs. These bristles are of moderate and rather different lengths; the length 

 of these bristles was observed to be rather different in a number of species, but within each 

 species it was subject to verv slight variations. The fifth joint has only one bristle, ,,the sensory 

 bristle of the fifth joint". In all the species of this genus that were investigated by me this 

 bristle consisted of a rather powerful, densely annulated trunk, of about uniform thickness, 

 differing somewhat in length in different species and having disto-anteriorly six subequal and 

 rather thick sensorial filaments placed closely together, of about the same length as or somewhat 

 longer than the trunk of the bristle. In a number of species there is an additional sensorial 

 filament on this bristle (thus making seven altogether) at about the middle of the anterior side 

 of the trunk; this sensorial filament is considerably narrower than the six former ones and is 

 in most cases not quite half the length of the trunk of the bristle. All these sensorial filaments 

 are of about a uniform thickness and are distally rounded, almost completely hyaline, bare and 

 provided with a short, fine sensory hair at the point. — It is to be noted that J. A. CUSHMAN, 

 1906, pi. 29, fig. 22 draws this bristle as simple without any lateral filaments, although sensorial 

 filaments are drawn on the bristles of the end joint in the same figure.* — The bristle on the sixth 

 joint was of the same type in all the species of this genus that were investigated by me, being 

 in most cases somewhat longer than the total length of the three distal joints, rather powerful 

 and furnished with short hairs. The small end joint, which is in most cases rather strongly 

 chitinized, has six or seven bristles. The a-bristle, situated anteriorly, was, in all the species 



* C. Claus stales, 18"6, p. 'j:;, tliat iu .1. m-'iiis this l)ristlr lias live seiiMnial tihiinerils, l_>iil he draws six; 

 evidently this writer eounts one filament as the ..liindv" of a hristle, a metluid whieh is perhaps the right one from 

 a theoretical point of view, but whicli has been rejected in this work for practical reasons: it is almost impossible to 

 decide which of these filaments is the distal part of the bristle, all of them being perfectly similar. 



