NERVOUS SYSTEM IN PELECYPODA 



207 



osphradia, and viscera generally, forming a special genital gang- 

 lion in connexion with the reproductive organs. The principal 

 ganglia of the Dibranchiata are still more concentrated, even 

 the visceral loop being possibly united with the rest in forming 

 an unbroken mass ip. which scarcely any trace of commissures 



Fig. 106. — Nervous system of Cardium edule L. : a.m, anterior adductor muscle; 6?', 

 branchiae; br.n, branchial nerve; eg, eg, cerebral ganglia ; c.p.c, cerebro-pedal 

 commissure; c.v.c', cerebro-visceral commissure; c.v.c, cerebro-visceral commis- 

 sure of mantle ; l.p, labial palps : m, mouth ; p.g, pedal ganglion ; p.m. posterior 

 adductor muscle ; v.g, visceral ganglion. (After Drost, x 3.) 



can be detected. The pedal ganglion becomes separated into 

 two portions, one of which innervates the arms, the other the 

 funnel. Two peculiar ganglia (the stellate ganglia) supply a 

 number of branching nerves to the mantle. • 



E. L. Bouvier, Systeme nerveux, morphologie generale et classification des 

 Gasteropodes prosobranches : Ann. Sc. Nat. Zool. (7), iii. 1887, pp. 

 1-510. 

 J. Brock, Zur Neurologie der Prosobranchier : Zeit. wiss. Zool. xlviii. 1889, 



pp. 67-83. 

 0. Biitschli, Bemerkungen iiber die wahrscheinliche Herleitung der Asym- 



metrie der Gasteropoda, etc. : Morph. Jahrb. xii. 1886, pp. 202-222. 

 B. Haller, Zur Kenntniss der Muriciden. I. Anatomic des Nervensystems : 

 Denksch. Math. Nat. Kl. Ak. Wien, xlv. 1882, pp. 87-106. 

 „ Untersuchungen iiber marine Rhipidoglossen. II. Textur des 

 Centralnervensystems und seiner Hullen : Morph. Jahrb. xi. 

 1885, pp. 319-436. 



