262 EDWARD S. MORSE. 



Nucula and Yoldia and showed also the primitive condition of 

 the gills in these genera. Pelseneer has united Solenomya, 

 Nucula, Leda and Yoldia in an order under the name of Proto- 

 branchia, forming the lowest order in Lamellibranchs. It is 

 interesting to observe that, while other genera of this low order 

 vary greatly among themselves and from each other, Solenomya 

 remains fixed in character despite the wide variation in size 

 among the species and their wide distribution in space. 



With the exception of the incomparable work of Deshayes, 2 

 that of Stempell 11 and Pelseneer 8 on Solenomya togata and that 

 of Drew 3 on Solenomya velum there have been very few obser- 

 vations on the anatomy or habits of the living creature, and most 

 of the records are derived from accounts of previous observers, 

 and these were in many cases incorrect. Gould says the foot 

 of the animal protrudes behind, whereas it protrudes in front; 

 that the edge of the mantle opening is fringed and that two of 

 the fibrils are larger than the others, which is incorrect, as 

 regards our species and that the palpi are triangular, whereas 

 they are long, narrow and semi-tubular. Stimpson's description, 

 though brief, is without error. Professor George N. Perkins, 9 

 in his " Molluscan Fauna of New Haven," a memoir teeming 

 with details concerning the soft parts of Mollusca and their 

 habits, has given one of the best accounts of Solenomya ever 

 published in this country. Carpenter, in his lectures on Mollusca, 

 says the mantle is closed in front, whereas it is wide open, and 

 that there is a tail on each side of the external opening. Cooke 

 mentions the two long tentacles springing from the siphonal 

 orifice. Stempell figures in S. togata two papilla? much longer 

 than the other siphonal processes. 



There is a puzzling discrepancy in the figures of the siphonal 

 tentacles of Solenomya togata as portrayed by various authors. 

 Philippi 10 figures 6 1 . togata with short siphonal papillae resembling 

 a rosette. Pelseneer, 8 in his contributions to the study of 

 Lamellibranchs, figures this species without a trace of long 

 siphonal tentacles. In his introduction to the "Study of Mol- 

 lusca" he gives a figure of S. togata with a pair of siphonal 

 tentacles 17 mm. long. This figure is however copied from 

 Deshayes' 2 "Natural History of Mollusca." It is probably 



