ASCIDIAIS'S COLLECTED BY THE YACHT ' GLIMPSE,' 1881. 531 



mities of the anterior end. Prom a consideration of the external 

 appearance only, this form would certainly be referred to a diffe- 

 rent species from the typical blister-like Styela grossularia ; but 

 the internal characters are the same in both. The oblong variety 

 shows the peculiarly abnormal branchial sac, with a single well- 

 developed longitudinal fold at the dorsal end o£ the right side, the 

 other seven, being rudimentary and represented merely by one or 

 more rows of narrow meshes formed by an approximation of two 

 or naore internal longitudinal bars. In the specimens from Cowes 

 and Southampton the dorsal tubercle is of the ring-like type some- 

 times found in this species*. 



The specimen from the Orwell has several young individuals of 

 different sizes adhering to the outer surface of the test. These are 

 neither markedly of the typical squat nor of the elongated form. 



Styela aggregata, O. F. Midler. 



This interesting species was obtained in considerable quantity 

 in July at Dartmouth, just inside the harbour off Grunfield, in 

 3 or 4 fathoms of water. The specimens were found adhering 

 together in thick-set clusters on pebbles and dead shells. The 

 individuals did not exceed half an inch in length. 



Dr. Sorby says in his notes : — " This is a charming and attrac- 

 tive species. When living, the colour is a peculiar orange, of a 

 fine clear tint, deeper on the long wide openings. When in water, 

 alive, and seen in some positions, it looked like a small terra- 

 cotta vase; but did not live long in my aquarium." 



This species was first found in British seas by Prof. Edward 

 Forbes at Dartmouth, but in rather deeper water, 12 fathoms. 

 He referred it to the Ascidia aggregata of the ' Zoologia Danica,' 

 and described it briefly in his ' British Mollusca,' vol. i. p. 41, 

 giving also a figure. His specimens were considerably larger than 

 ours, but did not differ otherAvise. The species has since been 

 more fully described by Kupfferf and TraustedtJ. These northern 

 specimens, if the same species, seem to be much larger than 

 ours, and to have a stronger and more corrugated test. Kupffer, 

 however, remarks upon the variability of the species ; consequently 

 the Dartmouth specimens, it adult, may be a small and smooth- 

 skinned variety. 



* Herdman, " On the ' Olfactory Tubercle ' as a specific character in Simple 

 Ascidiaiis," Proc. Eoy. Pbys. Soc. Edin. vol. vi. p. 254, 1880-81. 



t ' Jahresberichte der Kommission zurUntersuchung der deutichen Meere in 

 Kiel.' Berhu, 1874. VII. Tunicata. 



+ ' Oversigt over de fra Danmark og dets uordlige Bilande kjendte Ascidia 

 Simplices,' Kjobenhavn, 1880, p. 16. 



