4-20 



TAGK SKOOSHKHG 



otluT ami almost parallel, iioth coiitinuinjr down to tlir nisliuin. Tin' tun diIkt ridges run nioif 

 parallel to tin- lon^itmlinal axis of tlic siii'li. one sonicwlKil above, the other somewhal hehiw 

 half the height of the shell. The former eontin\ies anteriorlv to tlie rostrum, where in most 

 cases it joins the ilorsal ridge; posteriorly it joins the ridge that runs along thi- ventral margin 

 on the posterior beak-like process of the shell; the anterior part of this ridge is weakly and i'airlv 

 uniforndy curved tlorsally; behind the middle of the shell, on tiie other haiul, it is very irregular 

 with at least two very striking, nodose, projecting corners. The latter, the ventral one of the ridges 

 that run more parallel to the longitudinal axis of tlie shell, is almost straight and suddenU- comes 

 to an end posteriorly a short distance in front of the posterior beak of the shell with a rather 

 strongly projecting protuberance; anteriorly just behind the rostral incisur it is joined by means 

 of a low but ilistinct transverse ridge both to the ridge running most dorsally to it and to the 



Fig. LXXVII. — Ph. ( Scleroconcha) Appelloji n. sp., $. — I. Left valve seen freiii Uie side (in reflected 



light); 23 X. 2. Shell seen from below; \'t,h X. 



ridge that runs along the ventral margin. The foveolae are sometimes considerably less developed 

 than is shown in the accompanying figure. The ridges, like the bottoms of the foveolae, have 

 a sculpture with small cavities, sometimes very difficult to observe (in some cases not even 

 existing?). The surface of the shell is sparsely furni.shed with small hairs, more numerous and 

 somewhat longer near the margin of the shell. Pores of the surface are found to a moderate 

 number; they are small and difficult to observe. Seen f r o m i n side the posterior beak- 

 like process appears to be slightly hollowed out in the shape of a siphon. Medial bristles: 

 The row of bristles on the rostrum is rather .sparse; a number of bristles in this row do not seem 

 to have any long distal secondary bristles. The bristles on the posterior portion of the list are 

 difficult to observe with certainty; they seem to exist in moderate number and not to be arranged 

 in clear groups. Between the list and the posterior margin of the shell no bristles seem to occur, 

 nor is any pocket-like formation observable here. 



First antenna (fig. 4): — Of the three bristles on the second joint the posterior 

 one is the longest, being in most cases about as long as the total length of the third to the fifth 

 or the third to the sixth joints; the lateral one is the shortest, in most cases about as long as 

 the total length of the third and fourth joints. The third joint has two anterior bristles and one 



