312 Dr. W. C. M'Intosh on the. 



Order Phylactol^mata. 

 Suborder PEDICELLINEA. 



Family Pedicellinidse. 

 Genus Pedicellina, Sars. 



PedicelUna echinata^ Sars ; Johnst. Brit. Zooph. p. 382, 

 pi. 70. f. 5. 



On the branclies of Ceramium ruhrum and other littoral 

 algae and zoophytes ; abundant. 



Class II. TUNICATA. 



Comparatively few Ascidians have been procured ; indeed 

 the department is in such a condition at present (as to specific 

 identification) that a much greater amount of time would have 

 been required for their elucidation than was available. The 

 late Mr. Joshua Alder most kindly looked over the collection, 

 and named those requiring identification in his usual con- 

 scientious manner ; and it is to be hoped that the work on 

 these forms by him and the late Mr. Hancock (one of the 

 best minute anatomists this country has produced) will soon 

 be published. The most abundant simple form is the Ascidia 

 sordida of Alder and Hancock, which is thrown by storms 

 on the West Sands in large numbers, attached to sea- 

 weeds, sticks, shells, and other objects. A. intestinali's is also 

 procured in this manner as well as between tide-marks ; 

 Pelojiaia corrugata and MoJgida arenosa, A. & H., affect deep 

 water only, and rarely occur during storms. The compound 

 forms are common under stones between tide-marks and in 

 the laminarian region : but much yet remains to be done in 

 this respect at St. Andrews. Though Ascidians on the ex- 

 posed parts of the east coast of Scotland are for the most part 

 rare in the laminarian region and between tide-marks, they 

 are common in still muddy waters on the west coast and in the 

 Hebrides, and in water which cannot but be slightly brackish, 

 as at the head of Loch Portan near Lochmaddy, where they 

 are both abundant and large ; they are also numerous and 

 large between tide-marks at Herm and in the rich waters 

 around the Channel Islands, as well as in the Zetlandic 

 voes. 



