[m'cmurrich] notes on SOME CRUSTACEAN FORMS 51 



the probable affinities of the larvae, arriving at the conclusion that 

 they undoubtedly belong to Cirrhipedan forms and, by a process of 

 exclusion, finally regarded them as the young of unknown forms 

 probably related to Proteolepas and therefore belonging to the group 

 Apoda. The evidence upon which this determination is based is, 

 however, by no means conclusive, since it is entirely negative in 

 character, and the exact affinities of the larvae are still an open question. 



Examples of the Kiel form, which Hansen designates by the 

 numeral IV and which may therefore be provisionally known as the 

 ylV larva, were later obtained by Apstein'^ and Lohmann,^ but these 

 authors contented themselves with a mere record of the capture of the 

 forms, without adding to our knowledge of their structure or relation- 

 ship. 



It was a matter of some interest to discover in the plankton of 

 Passamaquoddy Bay larvae of Hansen's y type apparently identical 

 with the ylV larvae from Kiel. They occurred in small numbers, 

 though somewhat more frequently than in the Kiel collections, and 

 were taken at various intervals throughout the winter and summer 

 months. The record of capture during the season 1915-16 is as 

 follows : — 



Dec. 4th Station 6' 1 ex. 



Feb. 5th " 10 1 " 



April 5th " 10 3 « 



April 17th " 10 1 " 



April 25th " 10 9 " 



May 1st " 6 2 " 



May 31st " 10 2 " 



June 8th " 10 2 " 



June 14th " 10 3 " 



June 22nd " 10 4 " 



June 29th " 10 1 " 



It will thus be seen that the occurrence of the larvae apparently 

 reaches a maximum in April, But continues until the end of June* 

 and that individuals never appear in large numbers, nine being 

 the largest observed in any one collection. In the total number (29) 

 obtained only two stages of development were represented, although 



*C. Apstein. Plankton in Nord — und Ostsee auf den deutschen Terminfahrten. 

 Wiss. Meeresuntersuch. Abth. Kiel. IX, 1905. 



''H. Lohmann. Untersuchungen zur Feststellung des vollstandigen Gehaltes 

 des Meeres an Plankton. Wiss. Meeresuntersuch. Abth. Kiel. X., 1908. 



'Station 6 was in the "River" immediately opposite the Biological Station and 

 Station 10 off West Light in Passamaquoddy Bay, near the entrance to St. Andrews 

 Harbour. 



^It may be stated that the collections were made on the average weekly, so that 

 from April 5th, until June 22nd. examples were found on every occasion except on 

 April 11th and on May 15th, 19th and 25th. 



