103 



Tectibranchiata. 



Aplysiidae. 



Aplysia (L.). 



Aplysia immunda Bgh. n. sp. 



PI. 1, Figs. 1—8. 



One specimen was taken by Dr. Mortensen on February 17th 1900 at Koh Kahdat 

 on a floating alga; on being set in spirit it poured out a carmine fluid from below the 

 dorsal shield. 



The length of this specimen was 17 mm , the breadth 9 mm and the height 8™®; the 

 mantle-shield was S mm long, the gill-slit 14™" and the gill 5°™ long. The sole of the 

 foot was 5 mm broad. — The ground colour of the specimen was whitish , but partly op- 

 pressed through a dark-gray or gray colour, forming a network on the sides of the foot- 

 lobes; in this network are again seen many round whitish spots. À similar colouring was 

 found on the anterior part of the back and on the head. Some sparingly scattered black 

 round spots formed a contrast to this colouring (fig. 1). The mantle (the dorsal shield) 

 showed a similar, but much lighter, net -like colouring, also with scattered black 

 spots ; from the anterior margin of the mantle a median black band ran some way 

 forward. The inside of the foot-lobes was also whitish, but with strong, black, sparingly 

 communicating, perpendicular bands. The gill whitish. The sole of the foot light dirtily 

 whitish. 



The form was elongated. The lobes of the foot reached through two thirds of 

 the length of the animal quite to the end of the body, and were, especially in the middle, 

 rather high (3 mm ). 



The shell was 8 mm long, and of a breadth of 6"™; it was calcareous, but quite 

 thin, and therefore it had been broken into several pieces. 



The central nervous system, as in the typical Aplysia, showed the roundish 

 cerebral ganglia, connected by a not quite short commissure; the pleural ones were of 

 about the same size; behind these latter the pedal ganglia were found, more than twice 

 the size of the others , and connected by a commissure , longer than the diameter of 

 the ganglia. 



The otocysts had a diameter of - I2 mm . Before the fore end of the gill was 

 seen a longish, yellow spot (Ospihradiumï). 



21* 



