1 ;ini si)nu>\vli;i( (liml)tfiil alxuit llir liiiiniild^izatKHi ul llu' niasl icitmy pad and llic oxal 

 cavitv on the pars inrisiva on tho coxali- in tliis genus. Does tlic masticatory pad in this j^cnus 

 correspond to tho niastioatorv pad -\- i\\r part surioundod by tlic hristlcs and hairs or only 

 to the former in the genus t'ouchoecia': And in the hitter case does tlic part surrounded by the 

 bristles and hairs in the latter genus correspond to the oval cavity in Euconchoecial It does 

 n<>t seem possible at j>rcsent to answer these questions with lull certainty. 



Euconchoecia Chiercliiae G. W. Muller. 



? Euconchoecia Chierchiae, C. W. Mi'LLKl^ 1890a, p. 277; i)l. XXVITT. figs. 1—10. 



Paracouchoi'cia ohlonga, P. T. C'LE\E, 1900, p. 40. 



Euconchoecia Chierchiae, G. S. BRADY, 1902 a, p. 190; pi. XXIV, figs. 9—15. 

 ? ., „ (part.), (J. W. MtlLl.ER, 1912, p. Dti. 



Description: — .M a 1 e: — 



Shell: — Length, 1,15 — 1,25 mm. Length : height about 2:1; length : breadth about 

 2.;} : 1. Seen f r o in the si il e (fig. 1), it is moderately elongated, with its greatest height 

 somewhat in front of the middle and the anterior part of the shell somewhat, though rather 

 slightly, larger than the posterior part. The ventral margin is moderately strongly and imiformly 

 curved and passes without corners into the anterior and posterior margins. The posterior 

 margin is also uniformly and moderately curved; it forms an angle of about 90" with the dorsal 

 margin. At the posterior dorsal corner the right valve is in most cases* armed with a moderately 

 long, narrow spine, more or less pointed distally. The left valve is more or less rounded here, 

 armed in most cases with a very small spine (fig. 4) ; the latter is sometimes quite absent, however 

 (as in fig. 8 of the female) ; in exceptional cases (cf . p. 754 below) both valves have a well developed 

 spine in this corner. The rostrum points almost straight forward; it is rather broad and symmetri- 

 cal (fig. 5). The shoulder vault is rather small, well rounded, not wing-shaped. Seen 

 from below (fig. 2), the shell is somewhat lentil-shaped, with its greatest breadth somewhat 

 in front of the middle and its anterior ])art distinctly larger than the posterior part; it is rather 

 broadly rounded anteriorly and grows narrow rather rapidly posteriorly, where it becomes 

 pointed; the side-contours are rather evenly curved. In the specimens investigated by me 

 the surface of the shell had no perceptible sculpture and no hairs. There are no 

 signs of a hinge-socket or a hinge-tooth postero-dorsally. Seen from inside: The 

 selvage* is very narrow and extremely difficult to verify with certainty; as far as I could 

 observe it had a whole margin throughout its length, even on the rostrum. The lamellae of 

 the shell are exceedingly thin; the part at which they are joined is narrow. 



First antenna (fig. 12): — The first joint has disto-ventrally a rather large, 

 verruciform, rounded process. (A process of about the same kind is found in all the males of this 

 genus in which this antenna is known; is it a generic character?) The fourth joint has ventrally 

 somewhat more than twenty (21 — 24 found) sensory bristles, arranged in three longitudinal 



* Cl. Ihe remark on Uiis species, p. 752 below. 



