bloomer: ANATOMY OF CERTAIN SPECIES OF SOLENIDAE. 8^ 



The viscero-parietal ganglia atv situated anteriorly to the posterior 

 adductor muscle, and between the l-ifurcUions of the retractor pedis 

 posterior muscle. The branchial nerves run laterall}- direct to the gills. 

 Each ganglion apparently gives rise to one posterior pallial nerve, which 

 passes along the ventral surface of the posterior adductor muscle to the 

 proximal portion of the siphon. There do not seem to be so many large 

 branches as in A', xtriijillatux. It is not possii le to make out the pedal 

 ganglia or the circumj^allial nerves. 



Cirndafonj ^ijdeiii. — The heart is situated over the protractor pedis 

 posterior muscle, more posteriorly than in .V. atritiillahix. 



On the structure of the gills of ' olen Ridewood states that "in the five 

 species of Solen examined the lamellae are heterorhabdic and plicate, the 

 plication being shallower in Solcri on'entaIi-'< than in the others. The numbers 

 of filaments in a plica are nearly the same in the two demibranchs and run 

 approximately 26 in ^o/m nu/ina 17 in >o/e« cn.^is, 12 in Solen /ones i, 22 in 

 Solen (Solena) rudiK and 16 in >olen (Pharella) orientalis. In Solen rudis 

 alternate interlamellar septa fail to reach more than half-way up the demi- 

 branch, but in all the other four species rise high." 



EXPLANATION OF PLATE X. 



Fij,'. I. Solfciiiiiis (lonihcyi, Lam. View from tbc right side, showins» tlie aliment- 

 ary canal, &c. Natural size. 



I' '.^- -• .. ,, Longitudinal section of the stomach, showing 



internal structure of the left side, x lA. 



'"'g'- 3- ,, ,, Longitudinal section of the stomach, sliowing 



' internal structure of the right side, x 1^, 



Eig. 4. .S'(i/(7/ conicns, Lam. Exiernal view of the anteiior end oi the right 



mantle lobe, 



^'•i- 5 Soldi ^i^oiildi. Com-. External view of the anterior end of the right 



mantle lobe. 



Fig. 6. Ciillclliis ia-i'iiiiiciis, Lam. View from the right side, showing the alimen- 



tary canal, &c. Natural size. 



Eig. 7. Soliii (SoUihi ) riiiiis, C. U. .\dA\us View from [the right side, showing the 



alimentary canal, &c. Natural size. 



^'^'A- ^' 1. „ Longitudinal section of the stomach, showing 



internal structure of the left side, x 2. 



•""'j^- 9' ,. ,, Longitudinal section of the stomach, showing 



internal structine of the right side, x 2. 



