- of South Devon and South Cornwall. 473 
Fauna’ must be referred to the Mimosella. Mr. Couch himself 
remarks upon the discrepancies between his own account of this 
species and those given by Ellis, Fleming, Thompson, and 
Johnston, and says of the form which he had in view, “If we 
suppose their descriptions to have been taken from injured spe- 
cimens, this in a similar condition closely resembles them ; 
otherwise it must be considered a new species.” He does not 
notice the mobility of the cells, or their biserial arrangement; 
but the characters which he gives are those of the Mimosella, 
and not of the Valkeria. His figure also is evidently intended to 
represent the former. 
In Dr. Johnston’s collection, now deposited in the British 
Museum, there are specimens of the Mimosella which he had 
received from Mrs. Griffiths, ranked under Valkeria Cuscuta. 
Mimosella gracilis grows in tangled masses on the Halidrys. 
6, BowrerBank1A, Farre, 
B. imbricata, Adams. 
Both forms occur—the densa of Farre, and the erect and 
branched variety, which Mr. Alder is inclined to consider speci- 
fically distinct. The former is met with abundantly in tide- 
pools, growing in small tufts on the stems of Corallina officinalis, 
and creeping over the under surface of stones between tide- 
marks. ‘The latter is also littoral, and is sometimes as much as 
3 inches in height. In colonies of the variety densa, cells are 
commonly found, laden with large yellow ova, one or two being 
present in each. In such cases the polypides have always dis- 
appeared, the eggs about filling the interior, 
7. AVENELLA, Dalyell. 
1. A. gigantea, Busk. 
Farrella gigantea, Busk, Mic. Journ. vol. iv. p. 93, pl. 5. fig. 2. 
Salcombe Bay, profusely investing Salicornaria farciminoides, 
The specimens are inferior in size to Mr. Busk’s from Tenby, 
but otherwise agree exactly with his description. 
2, A. dilatata, Hincks, Microsc. Journ. vol. viii. p. 279, 
pl. 30. fig. 7, 
On Flustra, probably not uncommon. 
There has been much confusion about the species of Avenella. 
The form here intended is a common parasite of various kinds 
of Flustra. I have it also spreading over shells dredged off the 
Isle of Man. In the latter habitat, the spinous expansions of 
the creeping fibre, which constitute a striking character, are 
well displayed; but on the Flustra they are detected with diffi- 
