ON THE TUNICATE BHIZOMOLGULA Gl-OBULARIS. 155 



12. Notes on the Tunicate Rliizomolgula glohularis Pallas *. 

 By R. KiRKPATRICK, F.Z.S. 



(Results of the Oxford University Expedition to Spitsbergen, 

 1921, No. 24.) 



[Received December l, 1922 : Read March 6, 1923.] 

 (Plate I.) 



Among the Tunicata collected by the Oxford University Expe- 

 dition to Spitsbergen, and sent to the Natural History Museuna 

 for identification, were 26 specimens of the small sandy Simple 

 Ascidian Rhizomolgula glohularis Pallas. As the material is 

 fairly well preserved, the writer believes a few anatomical notes 

 may be of interest. 



Description. — The specimens (PI. I. fig. 1) are somewhat tri- 

 angular in shape, and covered with fine sand ; the largest ai^e 

 about 10 mm. high, not including the stem-like basal process, 

 10 mm. broad and 3 mm. thick. The two orifices, one at each 

 end of a flat oval area, are usually barely discernible. 



Oral tentacles (PI. I. fig. 2): there are 8 large primai-ies, 

 8 secondary, 16 tertiary, and 32 quaternary, i. e. 64 in all. 

 Primary tentacles sickle-shaped, compressed laterally. 



Dorsal tubercle horseshoe-shaped with opening forwards and 

 to the left. 



Branchial folds six on each side, each with five inner longi- 

 tudinal vessels. 



Infundibula deep, with the long double spiral gill-clefts wound 

 in the same direction ; accessory gill-slits leather simple, commonly 

 with a single curve nearly flat. 



The hermaphrodite sexual gland in the loop of the intestine, 

 the minute oblong kidney, and the paired peduncular secretory 

 glands near the base of the endostyle, all on the left side excepting 

 the right secretory gland. 



Locality. Klaas Billen Bay, just above low-tide mark, i. e. ex- 

 posed to the air at low tide ; near by a line of large boulders 

 close to the Nordenskiold Glacier {G. S. Elton). 



The history of the genus Rhizovtolgiola is interesting. It was 

 founded by Bitter in 1891 for a new species of Molgulid from 

 Prince William Sound, Alaska, 20 fms., i. e. outside the Arctic 

 Circle. The generic characters were the existence of the 

 peduncle, the presence of six folds on each side of the branchial 

 sac, the deep infundibula with spiral gill-cleft, and the left-sided 

 position of the intestines and hermaphrodite sex gland, and the 



* [This title replaces the title published in the Abstract No. 236. — Ed.] 



