NO. 9 MARINE INVERTEBRATES, ALASKA — MacGINITIE IIQ 



New colonies were taken through the ice on February 14, 1949, at a 

 depth of 149 feet. This is a truly Arctic species that has been known 

 from eastern Canada, Greenland, Iceland, and the European, Russian, 

 and Siberian Arctic, but has not been reported previously from Point 

 Barrow. 



Another common species, probably Sertularia sp., was taken in 

 every haul from no to 477 feet, and large colonies were taken through 

 the ice on February 18, 1950, at 162 feet. The simple ascidian 

 Molgula griffithsi often grew on its stems and Foraminifera were 

 frequently found on it. (See "Reproduction Phenomena.") Colonies 

 of the treelike Thuiaria elegans Kirchenpauer, up to 200 mm. in 

 height, were dredged at Eluitkak Pass and at depths of 120 to 741 

 feet. Since this species has been known only from Flower Bay in 

 Bering Sea, the Point Barrow specimens represent a northward 

 extension of range into the Arctic. Another species of Thuiaria, possi- 

 bly T. lonchitis (Ellis and Solander), was common at depths of 80 

 to 477 feet. 



Suborder Leptomedusae 



Medusae of a species of Ohelia were taken in plankton tows in 

 August of 1948 and 1949. They were transparent, with brown gonads 

 and a pale, translucent, tan manubrium. In most specimens there 

 appeared to be a progression of development in the gonads in that one 

 gonad was small, another a little larger, the third fairly well developed, 

 and the fourth still more mature. One medusa had eaten a green 

 ciliated larva too large to be engulfed at one time and part of it was 

 projecting from the mouth while the cilia of the larva continued 

 beating. 



Other Leptomedusae were collected from shore by means of a net. 



Order TRACHYLINA 

 Suborder Trachymedusae 



The transparent Halistaura cellularia (A. Agassiz), with peach- 

 colored canals, was common about the middle of August and was seen 

 occasionally at other times. 



The most consistently abundant hydromedusa was Aglantha digi- 

 talis (O. F. Miiller), which was plentiful to extremely abundant at 

 times. Specimens were observed from the latter part of June, when 

 they were taken through holes in the ice, to the first week in Septem- 

 ber. On August 6, 1948, all sizes were present, ranging from young 

 specimens with gonads that were mere specks to full-grown ones with 



