PLATE 12. 



Fig. 1 . Reconstruction of anterior end of Strophomenia scandens. 



Fig. 2. Section through dorso-tcrminal sense organ of Ale.xandromenia valida. 



Fig. 3. Reconstruction of posterior end of Strophomenia spinosa, small specimen. 



Fig. 4. Reconstruction of posterior end of Chaetodcrma attenuata, showing ])rincii)al nerves 

 (brn) passing into the gill. 



Fig. 5. Reconstruction of anterior part of nervous system of Alcxandromenia agassizi. 



Fig. 6. Same of posterior end. 



