108 CATALOGUE OF 



Morch's diagnosis (121, p. 37) is a little more explicit: 



" T. oblique-ovalis, ventricosa, striis incrementisubtilissimis, 

 sulci increment! 5-6 remoti contasbulati [sic], cinereo-lules- 

 cente, intus cinerea ; umbones gibbosi." 



But Clesshrs description of bis Pisidium ylobulare (179, p. 532), 

 which comparison of authentic specimens shows to be the same, 

 conveys a more accurate notion : 



"Concha mediocris, rot undato-ovata, tenuis, subtiliter striata 

 flavo-cornea ; umbones prominentes, lati, rotundati ; liga- 

 mentum contectum ; dentes card. valv. sinistra3 2, posterior 

 brevis, tenuis, vix curvatus, anterior crassus, in angulum 

 curvatus, dens card. valv. dextrae curvatus, parte posteiiore 

 brevi, crassiore, parte anteiiore longiore, tenui." 



To this again must be added tbe details concerning the characters 

 of the hinge : 



Hinge (PI. II, f. 7; IV, f. 1) about f the length of the shell, 

 not very broad and not projecting much inwards, strongly 

 arched. 



ll.Y. ./. about \ the length of the hinge-line, narrow, fairly 



strong, slightly deflected inwards ; base fairly strong ; 

 apex central, prominent, acuminate ; ridges fairly 

 sharp, sloping about equally and steeply. 



a. TIL about ^ the length of, and parallel to a. /., narrow, 

 straight, inclined toward the shell-wall ; apex distal 

 side of centre, pointed, obtuse ; ridyes somewhat 

 rounded, descending equally and gradually. 

 3. lamelliforra, prominent, anterior end higher, sharply 

 flexed ; a fairly parallel to the shell-margin, b running 

 diagonally across the hinge-plate to its margin. 

 _2>, /. not quite 3 the length of the hinge-line, narrow, fairly 

 strong, straight ; base not strong ; apex nearer distal 

 end, fairly prominent, pointed, obtuse ; ridyes sharp, 

 sloping about equally and fairly gradually, 

 p. in. about -J- the length of, and parallel to p. /., narrow, 

 fairly strong, straight; apex about central, obtuse; 

 ridyes somewhat rounded, sloping about equally and 

 fairly gradually. 



L.V. 'i. //. about J- the length of the hinge-line, narrow, fairly 

 strong, curving with the shell-margin ; base fairly 

 strong; apex central, very prominent, very acuminate, 

 slightly distally directed ; ridyes fairly sharp, distal 

 exceedingly steep at first, then sloping gradually, 

 umbonal steep. 



2. triangular, prominent, base continuous with that of 

 a. ii.. apex backwardly directed. 



