Mollusks. 4431 



The following list of a beautiful tribe of Mollusks {Gasteropoda 

 Nudibranchiata), with remarks upon the different species, has been 

 kindly supplied by Mr. George Murray, whose name has already often 

 occurred in this paper. 



Doris tuberculata, {D. argo, Flem.) Frequent at Burghead, be- 

 tween tide-marks, where the practised eye will seldom fail to detach it 

 either in rock-crevices or beneath large stones. 



Doris Johnstoni. At Burghead, in the same situation as the 

 preceding; not common. 



Doris aspera. Common among the rocks at Burghead, where it is 

 found most abundantly during the greatest spring-tides. When these 

 occur their recess lays bare a portion of the rocky beach thickly 

 strewn with stones of all sizes, which are covered with sea-weeds and 

 zoophytes, and are protected from the violent action of the surf by an 

 outer ledge of rock accessible only at such periods, though its top rises 

 considerably above the water during ordinary tides. The space thus 

 imperfectly described constitutes a sort of intermediate territory 

 between the littoral and laminarian zones. In this highly favourable 

 locality, so abundant are the animals of the Nudibranchiate order 

 that a single tide has often sufficed to put the collector in possession 

 of hundreds of individuals, some of which are seldom found except in 

 deep water. Here D. aspera especially abounds. 



Doris bilamellata. Common between tide- marks at Burghead. 

 This species appears to be somewhat gregarious in its habits, occur- 

 ring generally in clusters. Not unfrequently a dozen or more have 

 been found on the same stone. 



Doris pusilla. The authors of the Monograph on the Nudibran- 

 chiate Mollusks, published by the Ray Society, — a work that can 

 never be referred to without the highest admiration, — state regarding 

 this species that the two individuals forming the subject of their 

 description were found " under stones at low-water mark, Torquay." 

 In a similar situation two were discovered at Burghead, in May, 

 1853, and another in the following September. Ranging therefore 

 from Devonshire in England to the " Devonshire of Scotland," 

 as Moray land has sometimes been styled, its distribution is pretty 

 extensive. It does not indeed appear to have yet been met with in 

 any intermediate locality, a circumstance perhaps less owing to 

 its rarity than to its minute size and consequent difficulty of detec- 

 tion, together with the paucity of observers interested in its class. 

 When the latter obstacle is removed — and it is cheering to note among 



