246 



CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



1. 



T. flectens 



Carpenter MS. 



Shell subelongate; 

 jugum acute. 



Surface with mi- 

 nute, not very close 

 granules, sparsely 

 subradiating. 



Median valves with 

 apices very promin- 

 ent; 



lateral areas 

 scarcely defined. 



Mucro conspicuous, 

 anterior. 



Sinus wide, flat. 



Valve i with 11, ii- 



vii with 1-1, viii with 

 11 slits. 



Color roseate. 



Girdle very mi- 

 nutely granulate. 



Length 8J4, width 

 6 mm.. 



Puget Sound, 

 Wash. 



"A variety from 

 Catalina Is. has the 

 posterior valve with 

 7, intermediate 1, an- 

 terior 8 slits, the 

 mucro less anterior." 

 (Carpenter). 



2. 



T. flectens 



Pilsbry, 1893 



Shell ovate-oblong, 

 moderately elevated. 



Surface minutely 

 granulate all over, 

 more closely on the 

 lateral areas, which 

 are otherwise scarcely 

 defined. 



M e d i an valves 

 squared and slightly 

 beaked. 



Mucro somewhat 

 anterior, rather pro- 

 jecting. 



Sinus slightly lam- 

 inate. 



Valve i with 8, ii- 

 vii with 1-1, viii with 

 7 slits. 



Color roseate or 

 deep blood red, more 

 or less maculated with 

 blue, the blue pre- 

 dominating on some 

 valves. 



Interior of a beauti- 

 ful deep rose color. 



Girdle rather dense- 

 ly covered with mi- 

 nute, elongated but 

 scarcely imbricating 

 scales. 



Ctenidia extending 

 2/3 or M the length 

 of the foot. 



Length 12, width 7 

 mm. 



Dredged off Vic- 

 toria, B. C. 



3. 



M. heathii 



Pilsbry, 1898 



Oblong, rather ele- 

 vated, carinated, the 

 side slopes nearly 

 straight. 



Surface finely and 

 evenly granulate, the 

 intervals very minute- 

 ly radially wrinkle 

 granulate. Anterior 

 valve with a few faint 

 shallow radial fur- 

 rows. 



Intermediate valves 

 very faintly radially 

 trisulcate at the sides, 

 the anterior two 

 grooves defining the 

 low, slight and incon- 

 spicuous diagonal rib; 

 lateral areas not 

 raised. 



Posterior valve with 

 semi-circular posterior 

 outline; the mucro in 

 front of the middle; 

 profile of surface in 

 front of it convex, be- 

 hind it decidedly con- 

 cave. 



S u t u r a 1 laminse, 

 sinus, and teeth about 

 as in M. lignosa. 



Posterior valve reg- 

 ularly ischnoid. 



Valve i with 8, ii- 

 vii with 1-1, viii with 

 7-8 slits. 



Color (1) olive 

 green with lighter 

 spots or rosy shading, 

 or (2) vivid red with 

 scattered blue spots. 



Interior deep rose 

 color or slightly pur- 

 plish. 



Girdle nude except 

 for 2 or 3 closely 

 grouped long bristles 

 at all or part of the 

 sutures, 1 on each 

 side of the head 

 valve, and 2 behind 

 the tail valve. 



Ctenidia about 25, 

 not extending quite 

 to the anterior end of 

 the foot. 



Length 25, width 

 12 mm. 



17 fms., Monterey 

 Bay, Cal. 



4. 

 M. heathii 

 Berry, 1911 



Oblong - elliptical, 

 rather elevated, car- 

 inated, the side 

 slopes nearly straight. 

 Surface finely, 

 evenly, rather dis- 

 tantly granulated. 



Median valves wide 

 and short, little 

 beaked. 



Posterior valve 

 with semi-circular pos- 

 terior outline; the 

 mucro anterior; pos- 

 terior slope concave. 



Insertion plates 

 continuous across 

 sinus. 



Posterior valve 

 regularly crescentic. 



Valve i with 8, ii- 

 vii with 1-1, viii with 

 S-8 slits. 



Color vivid red 

 with scattered blue 

 spots and valves v-vii 

 clouded with green- 

 ish. 



Girdle microscopic- 

 ally spiculose, bearing 

 also a long branching 

 bristle opposite each 

 suture, 2-5 in front of 

 the head valve, and 2 

 behind the tail valve, 

 with a peripheral ser- 

 ies of very small bris- 

 tles around the gir- 

 dle margin. 



Length 11, width 7 

 mm. 



15 fms., Monterey 

 Bay, Cal. 



