duction 
oranchiata. 
ibranchiata 
ella Lamarck . 
scapula (Martyn) . 
D. ecaudata (Rang) . 
D. teremidi (Rang) 
gigas (Rang) 
hasseltii (Férussac) 
hemprichii Ehrenberg 
guayaquilensis Petit. . 
elongata Sowerby . 
californica Stearns 
neira Sowerby . 
ella agassizi, sp. nov. 
ernal characters 
General form and color 
_ Dimensions 
Bertoot . 
ae one 
- Pallial a : 
Shell : 
__ Pharyngeal bulb 
~ Mandibles . 
5 @eadiia. . . 
z Palatal folds . 
matic characters of ie: Opidtho- 
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TABLE OF CONTENTS. 
Palatal spines . 
Salivary glands . 
Oesophagus 5 
Ingluvies and mente ston. 
ach : 
Liver and nite : 
Reproductive system . 
Ovotestis 
Small ermaphroditic diet 
Adnexed genital mass . 
Spermatocyst . 
Albumen and nidamental lands 
Large hermaphroditiec duct . 
Spermatotheca 
External spermatic groove ani 
penis . 
Nervous system : 
Central nervous system 
Cerebral ganglia . 
Cerebral nerves . 
Pedal ganglia . 
Pedal nerves . . 
Parapedal commissure . 
Pleural ganglia 
Pleural nerves 
Buccal ganglia 
Buccal nerves 
Parieto-visceral canta 
Visceral nerves 
Parietal nerves : 
Respiratory, circulatory, al excre- 
tory systems . 
316 | Literature ; 
318 | Explanation of plates 
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