GASTEEOPODES. 297 



a straight line ; the middle was irregularly circular, as if for casting a knot, 

 and each end prolonged. The rope is always solid and clumsy, and 

 above a line in thickness. The motion of Nautilines within the former 

 spawn of July 4th, was visible on the 18th under the microscope. 



This spawn is always of the purest white ; and the multitude of ova 

 such as to make it appear almost solid. It comes to maturity, and the 

 Nautilines are liberated in fifteen days. 



This animal is not common. 



PLATE XLII. 



FIG. 8. Doris (Goniodoris) nodosa, back. 



9. Belly. 



10. Tentaculum. 



11. Branchiae. 



12. Spawn. 



13. Spawn. 



14. Portion of spawn, enlarged. 



4. DORIS (ANCULA) CRISTATA. Plate XLII. Figs. 15, 16, 17, 18, 19, 20. 



An animal is described by Messrs Alder and Hancock under the 

 name of Ancula cristata, as given by a foreign naturalist, with which I 

 apprehend the following may be nearly identified. But I acknowledge 

 that there is such an enormous difference in the size of the magnified 

 figures in the work containing them and any specimens I have had, that 

 I feel some perplexity. A musquito magnified to the size of a partridge 

 ceases to resemble the original. 



Length seven lines ; breadth a line. Body thick, lanceolate. Head 

 somewhat hammer-shaped, front obtuse, with an obtuse prolongation to- 

 wards each side. Tentacula two, each originating from between two 

 slender flexible processes about half the length of the tentaculum. Un- 

 der half of the tentaculum smooth ; each side of the upper half deeply in- 

 dented on each side by about ten short leaves. The tentacula somewhat 

 clavate, with the tip cylindrical, and they are slightly recurved during 

 progression. Two minute black eyes are behind their roots. 



2p 



