THE NAUTILUS. 77 



papyracea the mantle is prolonged at the siphonal end but does not 

 surround the tubes like a collar, nor are its edges reflected. Pan- 

 dora trilineata has a translucent envelope surrounding the base of the 

 siphons and closely adherent. In Yoldia limatula and T. sapotilla 

 there are distinct lobes of the mantle flanking the sides of the tubes. 

 In Tagelus gibbus there are two projecting and rounded lappets 

 corresponding to the siphons. The siphonal collar of T. conradi, its 

 separateness from the tubes and widely reflected edge is, so far as I 

 know, unique among the lamellibranchs. Whether this feature 

 should constitute a generic character I am not prepared to say. Dr. 

 William StimpsonMn mentioning T. conradi says: "The absence 

 of an ossiculum in the species would seem sufficient to separate it 

 generically from other Thracise. But the animal resembles so 

 closely that of the large English species which possess the ossiculum, 

 that I have thought it best to consider the appendage unimportant." 



BIBLIOGRAPHY. 



1. Meyer and Mobius. Fauna der Kieler Bucht. 



2. Forbes and Hanley. A History of British Mollusca and their 



Shells. 



3. Gould and Binney. Invertebrata of Massachusetts. 



4. Report of Commissioner of Fish and Fisheries, 1871-72, Plate 



XXIV. 



5. Jeffreys. British Conchology. 



6. Couthouy. Monograph on the Family Osteodesmacea. Boston 



Journal Natural History. Vol. II, No. 2. 



7. Stimpson. A Revision of the Synonomy of the Testaceous Mol- 



lusks of New England. 



GUNDLACHIA HJALMARSONI PER. IN THE RIO GRANDE, TEXAS. 



BY GEO. H. CLAPP. 



The above-mentioned Gundlachia was picked out of drift debris 

 collected on the Texas side of the Rio Grande by Mr. R. D. Camp 

 of Brownsville, Texas. It is associated in the trash with thousands 

 of Bifidaria, Thysanophora, etcetera, over twenty-five species in all. 



