20 



MR MACDONALD ON THE ANATOMY OF THE HETEROPODA. 



Fig. 8. Brain and Organs of Sense of Firola. 



a.Uppercerebroids, send- 

 ing off anterior and 

 posterior branches. 



b. Lower cerebroids, giv- 



ing off motor nerves 

 to the eyes. 



c. Buccal nerves. 



d. Motor nerve of the 



eve. 



e. Optic nerves. 



/, Trunks communicat- 

 ing with the pedal 

 ganglia. 



g. Auditory nerve. 



h. Acoustic sacs. 



i. Lens. 



k. Body of the eye. 



I. Retina. 



Fig. 9. Lingual Dentition of Firola Lesueuri. 

 0. Rachis. | 1-3. Pleurae. 



Fig. 10. 



a. Buccal mass. 



b. (Esophagus. 



c. Tentacula. 



d. Eyes. 



e. Ear-sacs. 

 /. Pedal ganglia. 

 g. Swimming-plate. 

 h. Sucker-disc. 



Fie. 11. 



Cardiapoda in motion. 



i. Curious structure no- 

 ticed at p. 17. 

 k. Caudal process. 

 I. Visceral mass. 

 m. Heart. 

 n. Branchiae. 

 0. Penis. 



Lingual Dentition of Cardiapoda. 



0. Rachis. | 1' Small inner tooth of 



1-3. Pleurae. I first pleural series. 



PLATE n. 



Fig. 1. Atlanta. 



a. Mouth. 



6. Buccal mass. 



c. Tentacula. 



d. Tentacular (?) tuber- 



cle at the inner and 

 fore part of the 

 eye. 



e. Eyes. 



/. Cerebroid ganglia. 

 g. Ear-sac. 

 h. Salivary glands. 

 i. Pedal ganglia. 

 j. Propodium. 

 k. Mesopodium. 

 I. (Esophagus. 

 m. Penis, 

 n. Mouth margin. 

 0. Carinal fold of n. 

 ■p. Branchiae. 

 <^. Ciliated line. 

 r. Venous sinuses. 

 s. Vent. 

 t. Aquiferous pore \ 



u. Glandular organ, pro- 

 bably renal. 



V. E.xpanded orifice of 

 the sperm-duct. 



w. Auricle of the heart. 



X. Intestine. 



y. Ventricle. 



z. Anterior division of 

 aorta. 



a. Aortic axis. 



jS. Visceral artery. 



J. Stomach. 



h. Dilatation of sperm- 

 duct. 



£. Liver. 



^. Testicle. 



?j. Origin of retractor 

 muscle. 



6. Metapodium. 



/. Tongue-like process. 



X. Fossa. 



X. Operculum. 



/A. Vertical fold. 



Fig. 1'. Operculum of 1, magnified. 



a. Buccal mass 



muzzle. 



b. Tentacula. 



c. Eyes. 



Fig. 2. Oxygyrus. 



and I d. Propodium. 

 e. Mesopodium. 

 /. Metapodium. 

 g. Operculum. 



Fig. 2'. Operculum of 2, magnified. 



Fig. 3. Oxygyrus, n. s. 

 References as in Fig. 2. 



Fig. 4. Carinaria 



a. Buccal mass. 



b. Tentacula. 



c. Eyes. 



d. Ear-sacs. 



e. Impacted food in the 



gullet. 

 /. Pedal ganglia. 



g, Propodium. 

 h. Mesopodium. 



i. Metapodium. 

 k. Penis. 



I. Branchise. 

 m. Visceral mass. 



Fig. 4'. Shell and Viscera magnified. 



a. Gullet. I c. Branchise. 



b. Rectum. I d. Heart. 



Fig. 6. The Bachidian Plates characteristic of the 

 genera of Heteropoda. 



a. Firoloides. e and /. Two divisions of 



6. Firola Oxygyrus, probably 



c. Cardiapoda. distinct genera. 



d. Carinaria. g. Atlanta. 



Fig. 6. Lingual Dentition of Carinaria. 

 Fig. 7. Do. do. Cardiapoda. 



Fig. 8. Do. 



0. Rachis 



1-3. Pleurae. 



1'. Tooth common to Car- 



do. 



Atlanta. 



diapoda, Carinaria, 

 and Oxygyrus. 

 1". Tooth characteristic of 

 Atlanta. 



