Mr. F. Walker's Descriptions 0/ Aphides. 295 



mantle, one for the foot, and one in common, for branchiae and 

 anus. 



It must not be supposed that I have mistaken the functions 

 of this fissure, and that it only belongs to the anal apparatus. 

 This is not the case ; it is beyond doubt a common cavity for twf> 

 distinct purposes, viz. anal and branchial. 



Thus this apparently strangely-formed animal turns out to be 

 very similar to most of the bivalves, having the branchial and anal 

 openings close together, where they ought to be, at the posterior 

 end, and the anterior tube-like fold being nothing more than an 

 aid to the foot in locomotion. I should not be at all surprised if 

 the tube of Kellia suborbicularis, when closely examined (as it 

 shall be), turns out to be an open canal ; but whether this is the 

 case or not, it is not for branchial, but locomotive uses. 



From this examination it results, that the only essential dif- 

 ference between the two species is, that the one is viviparous and 

 the other oviparous. You will now be able to judge if the genus 

 Poronia must be adopted. 



In the twelve specimens no young were found, as in the summer- 

 time ; I therefore conclude that '' Alma Venus," as Lucretius 

 styles the goddess, does not influence the self-sufficing loves of 

 these moUusca until 



" species patefacta est verna diei, 



Et reserata viget genitabilis aura Favoni." 



I am, my dear Sir, most truly yours, 

 Ed. Forbes, Esq. William Clark. 



XXXV. — Descriptions 0/ Aphides. By Francis Walker, F.L.S. 

 [Continued from p. 53.] 



61. Aphis Ribis. 



Aphis Ribis, Linn. Syst. Nat. ii. 733. 1 ; Faun. Suec. 975 ; 

 Gmel. ed. Syst. Nat. i. 2201 ; Fabr. Syst. Ent. 734. 5 ; Sp. Ins. ii. 

 385 ; Ent. Syst. iv. 211. 7; Syst. Rhyn. 295. 7; Frisch, Ins. ii. 

 9. t. 14; Reaum. Ins. iii. 281-350. t. 22. f. 7-10; Hausm. 111. 

 Mag. i. 437. 2; Leuwenh. Arc. ep. 90. 545. t. 548; Blanck. Ins. 

 164. t. 14. f. D. 2; Schrank, Faun. Boic. ii. 1. 108. 1195 ; Sir 

 Oswald Mosley, Gard. Chron. i. 628; Kalt. Mon. Pflan. i. 39. 

 26. 



Ribifex, Amyot, Ann. Soc. Ent. 2"^® serie, v. 476. 



This Aphis feeds on Ribis rubrum, R. nigrum, R. alpinum, R. 

 grossularia, and R. uva crispa, from March till November. 



The viviparous wingless female. In the spring and when very 

 young it is dark olive-green, oval, short, and plump : the feelei-s 



