38 J. II. ORTON. 



glossus (a species of Ptychodera) shows the presence of well-marked 

 lateral cilia and smaller frontal or pharyngeal cilia. From the fore- 

 going observations it is a fair deduction that these lateral cilia produce 

 the main current of water through, the body of the animal, and that the 

 frontal cilia are concerned in some way in food-collection. It is also 

 highly probable that observations on this group of animals may now 

 demonstrate the function of the mucus, which is doubtless secreted by the 

 dorsal diverticulum, the gland in this group of animals corresponding to 

 Hatchek's pit in Amphioxus and the neural gland in Ascidians. 



OBSEEVATIONS ON THE AMMOCOETE OF PETROMYZON 



FLUVIATILIS. 



Some observations have also been made on rather late stages of the 

 Ammocoete of Petromyzon fluviatilis. It is well known that this larva 

 closely resembles Amphioxus in some respects. I have also learnt from 

 fishermen that these larvae will live in captivity for even a year by merely 

 changing regularly the water in which they are kept. It was therefore 

 thought probable that they might feed on Plankton in the same way 

 as Amphioxus. Two specimens were fed on carmine particles and then 

 preserved in 90% alcohol. On opening the branchial portion of the 

 alimentary canal it was found that the carmine particles had become 

 entrapped in mucus and were collected along the gill-bars and roof of the 

 pharynx. No particles, however, were found in the intestine. Neverthe- 

 less sufficient evidence was obtained to indicate that further observations 

 on the mode of feeding in younger forms might be highly interesting, and 

 an effort will be made to make such observations. 



THE MODE OF FEEDING IN SOLENOMYA TOGATA. 

 In view of the observations formerly made on the mode of feeding in 

 Nucula (see 5, pp. 467-70), similar observations undertaken upon any 

 other Protobranch promised to be interesting. Acting upon a happy 

 suggestion made by Sir E. Eay Lankester, I obtained living specimens of 

 Solenomya togata from Naples at the second attempt, and made the 

 following observations. An examination of this delicate little animal 

 through a microscope in water containing carmine particles readily 

 showed that as in Nucula the mantle cavity is divided into two chambers 

 when the animal is feeding. The food-current is drawn into the mantle 

 cavity at the antero-dorsal end and expelled posteriorly (see Fig. 7). 

 During the process of feeding the gills are extended so that their posterior 



