220 FAUNISTIG NOTES AT PLYMOUTH DURING 1893-4. 
a remarkable manner the most salient characters of the Notaspidea 
and Cephalaspidea. I have prepared figures of this little animal, a 
description of which will be published immediately. 
Several rare Nudibranchs have been taken, chief of which are the 
AMolid Berghia cerulescens and Hero formosa, Both forms inhabit 
the deeper waters outside the Breakwater, and the latter is by no 
means uncommon. Additional captures have also been often taken 
of Molidiella glauca and Platydoris planata, and, less frequently, of 
Amphorina cerulea, Antiopa hyalina, Embletonia pulchra, Herma 
bifida, and Thecacera pennigera. ‘The specific habits of most of 
these forms are still unknown, but in the case of two Dorids, 
Rostanga coccinea and Lamellidoris oblonga, the following observa- 
tions upon their habits may be useful. Just as Jorunna Johnstoni* 
lives among small Halichondriz#, upon which it feeds, and which it 
strikingly mimics in general and even detailed appearance, so I have 
found that Rostanga coccinea, which is of a bright scarlet colour, 
lives—in both senses—upon red encrusting sponges. ‘This species, 
which formerly seemed to be rare at Plymouth, I have been able to 
obtain easily by dredging or collecting in those places where its 
food-sponges are abundant. On the other hand, Lamellidoris 
oblonga lives not upon sponges, but upon Polyzoa of the genus 
Cellaria, especially the stouter species, the twigs of which it clasps 
firmly with its foot. This Dorid is not well described by Alder and 
Hancock, no doubt from their lack of a sufficient number of speci- 
mens from which to educe the characteristic features. The back 
normally shows a variable number of irregular, ring-like, dark spots 
(of which there are usually eight or nine more conspicuous than the 
rest), and round the entire periphery of the back there is a pigmented 
border, which has no sharply defined edges, but is a marked feature 
when a number of specimens are examined and compared. The 
edges of the rhinophoral fosse are raised into a slight rim or sheath 
provided with three tubercles. The chief differences between 
individuals for the most part concern simply the relative intensity of 
the brown pigmentation: the annular spots and border were indis- 
tinguishable in only three out of forty specimens. I first noticed 
this species on December 19th, 1892, when scores of specimens were 
taken from Cellaria trawled seven miles south of the Breakwater. 
With them were associated a few specimens of Lamellidoris pusilla 
and Lamellidoris prowima. 
Another small Dorid, whose back is strikingly marked by con- 
spicuous purple tubercles upon a field of yellow, seems to be new to 
science, and will be described elsewhere. 
* Garstang, Notes on the Structure and Habits of Jorunna Johnstoni, Conchologist, 
vol. ii, 1892. 
