1879.] NATURAL SCIENCES OF PHILADELPHIA. 127 



Dendronotus Dalli, Bergh. 



9. The tongue and its muscular mass (c) from the side; 6, radula ; 



c, tectum radulse. 

 10. The same from above; a, superior end of the radula; 66, 



muscular masses of the tongue; c, end of the descending 



sheath of the radula. 

 ] 1. Anterior rhachidian tooth, from above,* ^. 

 1*2. The same, from below,* ^. 



Dendronotus arborescens (0. F. Mull.). 



13. Hinder part of the cutting edge;* a, youngest part, ^p. 



14. Hook of a rhachidian tooth,* 3 p. 



15. A group of (5) follicles of the hermaphroditic gland, a, efferent 



duct,* iM. 



Flabellina iodinea (Cooper). 



1G. Part of three rows of plates, from above ;* a, rhachidian 

 6, lateral plates, 3 \. 



Plate III. 



Dendronotus arborescens (F.). 



1. Four lateral teeth ;* aa, doubled tooth, ^. 



Dendronotus Dalli, Bergh. 



2. The left mandible from the inside;* a, crista connectiva ; 6, 



superior process; c, processus masticatorius, ". 



3. The same with the same lettering,* ~. 



4. A part of the masticating edge,* ^f 2 . 



5. Thirteen outer plates of one of the posterior rows of the 



radula;* a, outermost plate, 3 ,. 

 G. A rhachidian tooth or plate from behind, ^p. 



Dendronotus purpureus, Bergh. 



7. The masticating process;* a, the point, ~. 



8. Median plate from the upper side,* ~-. 



9 Two median plates from the under side,* 3 p. 



10. The serrations of the right side of the median plate,* . 



11. Three lateral plates,* 4*. 



12. (a) Anterior part of the salivary gland ;* 6, duct, ~ 



