202 Dr. C. Collingwood on Nudibranchiate Mollusca. 



same spot at intervals of three and five years, and at last in 

 company with its congener, exhibiting the curious and interest- 

 ing spectacle of a small rock-pool containing an entire genus, 

 the species of which are — one a widely-distributed animal, whose 

 geographical range extends from there to the Mediterranean 

 Sea, the other apparently one of the most localized animals 

 upon the face of the earth. 



The value of local lists is now fully recognized ; and although 

 they can never be deemed perfect, inasmuch as enlarged research 

 and process of time may always be expected to bring to light 

 additional species, nevertheless the collection of such carefully 

 prepared lists is undoubtedly the best means of illustrating the 

 Fauna of a country, as well as of elucidating the geographical 

 range and distribution of animals. The following Catalogue of 

 the Nudibranchiate Mollusca of the Mersey and Dee may be 

 regarded as accurate and complete up to the present time. 



Catalogue of the Nudibranchiata of the Mersey and Bee. 



1. Doris tuber culat a. Mersey and Dee ; common. 



2. Johnstoni. Mersey and Dee; once or twice. 



3. proxima. Mersey and Dee ; common (found nowhere else). 



4. bilamellata. Mersey and Dee ; abundant. 



5. pilosa. Mersey and Dee; not uncommon. 



6. subquadrata. Dee; once (the second known specimen). 



7. depressa. Dee ; once. 



8. Polycera Lessonii. Between Mersey and Dee ; once. 



9. ocellata. Mersey and Dee ; occasional. 



10. Ancula cristata. Mersey and Dee ; common. 



11. Tritonia Hombergii. Mersey and Dee ; occasional. 



12. plebeia. Mersey and Dee ; occasional. 



13. Dendronotus arborescens. Mersey and Dee ; common. 



14. Doto coronata. Mersey and Dee ; very common. 



15. Eolis papillosa. Mersey and Dee ; common. 



16. coronata. Mersey and Dee ; common. 



17. Drummondi. Mersey and Dee ; very common. 



18. rufibranchialis. Mersey and Dee ; not uncommon. 



19. Landsburgii. Mersey and Dee ; rare. 



20. concinna. Mersey ; common (the second known locality). 



21. olivacea. Dee; once taken. 



22. ■ aurantiaca. Mersey and Dee ; common. 



23. picta. Mersey and Dee ; not uncommon. 



24. exigua. Mersey ; apparently rare. 



25. despecta. Mersey ; common. 



26. Embletonia pallida. Mersey (the only known locality) ; very rare. 



27. Antiopa cristata. Dee; occasional. 



28. Antiopa hyalina. Dee (the only known locality) ; very rare. 



15 Oxford St., Liverpool, 

 v August 1860. 



