Stiulios on m.irinc O=;lrac-oils 471 



just beliiiul the iiicisur tliere are rather few or a moderate number of scattered bristles, of whieli 

 those that are situated near the margin of the shell are moderately long, those situated farther 

 in more or less short. Along the middle part of the ventral margin of the shell there are a moderate 

 number of long or rather short, stiff bristles, most of which are arranged in a rather distinct 

 row running somewhat inside the ventral margin. Between the ventral half of the spine-bearing 

 list and the margin of the shell there are rather numerous moderately long, stiff bristles, some- 

 times arranged in a more or less distinct row. running about parallel to and somewhat inside 

 the margin of the shell, in most cases, however (as in the accompanying figure 3) arranged more 

 or less irregularly. Dorsally of these bristles there are a moderate number of scattered, very 

 short bristles right u}) to the doisal lioundary of the bristle-bearing list. About half-way between 

 and parallel to the posterior margin of the shell and the dorsal half of the spine-bearing list 

 there is a sparse row of six or seven broad pores; each of these pores is furnished with a freelv 

 projecting hyaline peg (1 was unable to ascertain with certainty the shape of these pegs). The 

 spine-bearing list is weakly undulated and is provided with about 32 to 35 hyaline spines, 

 varying somewhat in size, and with a close row of stiff and rather short bristles, varying somewhat 

 in length; on an average about three bristles were observed for each hyaline spine. Neither 

 on the right nor on the left valve was there a sharp edge similar to that described and repioduced 

 as characteristic of the posterior part of the right valve of A. spinifera (cf. this species, fig. 3). 

 First antenna (fig. 5): — This has six or seven joints; the third and fourth joints 

 are sometimes free, sometimes more or less strongly united. These two joints form together 

 one sub-rectangular joint, whose length is somewhat less than its height and rather considerably 

 less than the total length of the two following joints. The distal boundary of the fourth joint 

 is moderately concave. The anterior bristle of the second joint is about as long as the anterior side 

 of this joint. The third joint has six anterior bristles. Of these nos. 5 and 6 and sometimes nos. 

 3 and 4 as well are situated at the side of each other. Bristles nos. 1, 2, 4 and 5 are armed ventrally 

 with long, stiff secondary bristles; the secondary bristles on bristles nos. 3 and 6 are short and 

 fine, often pressed rather close to the bristle, so that they are sometimes rather difficult to observe 

 with certainty. The longer of the two postero-distal bristles of the fourth joint is somewhat 

 longer than the fifth joint, but somewhat shorter, however, than the total length of the fifth 

 and sixth joints. The stem of the sensory bristle of the fifth joint is about as long as or somewhat 

 shorter than the total length of the third to the sixth joints; it is provided with seven sensorial 

 filaments. Tlie end joint has seven bristles, the d-bristle is developed, unlike in most of the species 

 ill this genus. Tlie a-claw is decidedly longer than the anterior side of the two ne.xt distal 

 joints and is smooth. The f-bristle has five sensorial filaments. The c- and g-bristles have six 

 sensorial filaments. The d-bristle is in most cases considerably shorter and rather considerably 

 more slender than the e-bristle. Pilosity: The first and second joints have abundant groups 

 of short, exceedingly fine, stiff hairs — only just suggested in the adjoining figure — the antero- 

 distal part of the second joint seems, however, to be always without hairs. There are no hairs 

 along the distal boundary of this joint. 



Second a n t (> n n a : — Tlie j) i- o t o p o d i t e has distally a very short bristle 

 on the inside close to the exopodite. Tiie end joint of the exopod ite has four bri.stles 



