DEEP-SEA PROTOBRANCHIA (BIVALVIA) 



41 



tulous space below umbo, anterior plate follows curvature of 

 antero-dorsal margin, posterior plate with slight convex arch, 

 equal number of teeth on each plate, teeth with prominent 

 dorsal arm and reduced ventral arm. 



Prodissoconch length: c 170 |xm. Maximum recorded shell 

 length: 4.62 mm. 



Shell measurements (mm) & ratios are as follows:- 



Length 



Height 



Width 



H/L 



W/L 



PL/TL 



2.56 

 2.60 



1.81 

 1.76 



1.26 

 1.22 



0.70 

 0.68 



0.49 



0.47 



0.51 

 0.53 



Internal morphology (Fig. 60). The siphons are com- 

 bined, with a single lumen present. A siphonal tentacle 

 occurs on the right side of the siphonal embayment. The 

 adductor muscles are unequal in size the anterior being one 

 and a half to two times larger in cross-section than the 

 posterior. Both are more or less oval in shape. The gills are 

 well-developed with 13-16 plates. The labial palps are small 

 in the contracted state, extending about 1/4 distance across 

 body, and have 8-10 moderately narrow palp ridges. In 

 contrast the palp proboscides are well-developed. The pedal 

 ganglia are large and elongate, similarly the visceral and 

 cerebral ganglia are also well-developed. They are club- 

 shaped with the cerebral ganglia being slightly larger than the 

 visceral. The foot is long and narrow, with a large byssal 

 gland in the heel. The stomach is large and there is a single 

 hind gut loop on the right side of the body. 



Yoldiella inconspicua inconspicua Verrill & Bush 1898 



Type locality. Off Martha's Vineyard, 318 fm. Original 

 specimens were taken from North American Basin between 

 Lat. 42°33'N, Long. 69°58.5'W and Lat. 35°12.10'N and 

 74°57.15'W by the U.S. Fish Commission Steamers Fish 

 Hawk and Albatross. 



Fig. 60 Yoldiella extensa. Lateral view from the right side of the 

 internal morphology of a specimen from Sta. 245 Argentine 

 Basin. (Scale = 1.0 mm). For identification of the parts see Fig. 

 34. 



Type specimen. Holotype: U.S. Natl. Mus. No. 48867. 



Yoldiella inconspicua Verrill & Bush 1898, p. 869, pi. 79, 



Figs. 5-3. 

 Yoldiella nana Waren 1989 (in part), p. 227. 



Material. 



Cruise 



Sta 



Depth No 

 (m) 



Lat 



Long 



Gear Date 



WEST EUROPEAN BASIN 



Sarsia 



S44 1739 



11 



43°40.8'N 



3°35.2'W 



ED 



16. 7.67 





S50 2379 



343 



43°46.7'N 



3°38.0'W 



ED 



18. 7.67 



Jean Charcot DS20 4226 



2 



47°33.0'N 



9°36.7'W 



DS 



24.10.72 



(Polygas) 



DS21 4190 



3 



47°31.5'N 



9°40.7'W 



DS 



24.10.72 





DS22 4144 



3 



47°34.1'N 



9°38.4'W 



DS 



25.10.72 





DS28 4413 



2 



44°23.8'N 



4°47.5'W 



DS 



2.11.72 



Chain 106 



316 2173- 

 2209 



20 



50°58.7'N 



13°01.6'W 



ES 



18. 8.72 





318 2868- 



72 



50°04.9'N 



14°23.8'W 



ES 



20. 8.72 





2890 





50°05.3'N 



14°24.8'W 









323 3338- 



16 



50°08.3'N 



13°53.7'W 



ES 



21. 8.72 





3356 





50°08.3'N 



13°50.9'W 









326 3859 



3 



50°04.9'N 

 50°05.3'N 



14°23.8'W 

 14°24.8'W 



ES 



22. 8.72 





330 4632 



30 



50°43.5'N 

 50°43.4'N 



17°51.7'W 

 17°52.9'W 



ES 



24. 8.72 



Challenger 



10 2540 



1 



56°36.0'N 



11°04.0'W 



ES 



4. 7.73 



Jean Charcot DS41 3548 



5 



47°28.3'N 



9°07.2'W 



DS 



26. 8.73 



(Biogas III) 















(Biogas IV) 



DS55 4125 



58 



47°34.9'N 



9°40.9'W 



DS 



22. 2.74 



(Biogas V) 



DS66 3480 



3 



47°28.2'N 



9°00.0'W 



DS 



16. 6.74 





DS67 4150 



1 



47°31.0'N 



9°35.0'W 



DS 



17. 6.74 



(Biogas VI) 



DS71 2194 



1 



47°34.3'N 



8°33.8'W 



DS 



20.10.74 





DS75 3250 



1 



47°28.1'N 



9°07.9'W 



DS 



22.10.74 





DS76 4228 



26 



47°34.8'N 



9°33.3'W 



DS 



23.10.74 





CP13 4134 



4 



47°34.4'N 



9°38.0'W 



CP 



23.10.74 





DS77 4240 



1 



47°31.8'N 



9°34.6'W 



DS 



24.10.74 





DS82 4462 



1 



44°25.4'N 



4°52.8'W 



DS 



29.10.74 



(Incal) 



DS01 2091 



2 



57°39.8'N 

 57°59.2'N 



10°39.8'W 

 10°41.3'W 



DS 



15. 7.76 





DS02 2081 



4 



57°58.8'N 

 57°58.5'N 



10°48.5'W 

 10°49.2'W 



DS 



16. 7.76 





C003 2466 



12 



56°38.0'N 

 56°37.3'N 



11°64.0'W 

 H°07.8'W 



CP 



17. 7.76 





C004 2483- 



9 



56°33.2'N 



11°11.3'W 



CP 



17. 7.76 





1513 





56°32.5'N 



H°12.4'W 









DS05 2503 



270 



56°28.1'N 

 56°27.6'N 



11°11.7'W 



n°02.o'w 



DS 



18. 7.76 





DS06 2494 



277 



56°26.6'N 



56°25.9'N 



11°10.5'W 

 11°10.7'W 



DS 



18. 7.76 





DS07 2884 



280 



55°00.7'N 

 55°01.0'N 



12°31.0'W 

 12°21.0'W 



DS 



19. 7.76 





DS08 2891 



58 



55°02.0'N 

 52°01.9'N 



12°34.6'W 

 12°33.4'W 



DS 



19. 7.76 





CP05 2884 



149 



55°00.4'N 

 55°00.9'N 



12°29.4'W 

 12°31.1'W 



CP 



19. 7.76 





CP06 2888- 



218 



55°02.3'N 



12°40.3'W 



CP 



19. 7.76 





2893 





55°02.6'N 



12°41.7'W 









KR06 2891 



1 



55°02.9'N 

 55°02.2'N 



12°43.7'W 

 12°39.0'W 



KR 



20. 7.76 





KR07 2891 



1 



55°02.9'N 

 55°02.2'N 



12°43.9'W 

 12°39.0'W 



KR 



20. 7.76 





CP07 2895 



488 



55°03.4'N 

 55°04.4'N 



12°46.2'W 

 12°46.7'W 



CP 



20. 7.76 





DS09 2897 



867 



55°07.7'N 

 55°08.1'N 



12°52.6'W 

 12°53.2'W 



DS 



20. 7.76 





CP08 2644 



135 



50°14.7'N 

 50°15.2'N 



13°13.5'W 

 13°14.8'W 



CP 



27. 7.76 





DS10 1719 



21 



50°12.7'N 

 50°13.2'N 



13°16.6'W 

 13°16.4'W 



DS 



27. 7.76 



