No.1139. DEEP-WATER MOLLUSCAVKIiBILL AND BUSJJ. 851 





TheLedida',as here understood, were divided into five subfamilies by 

 Fischer, namely: 



(1) Cucullellina- = Ctenodontidse Ball -f I'liltt'onrilo and ('iirdiolaria; 

 ("2) Sareptina?. (for Sarepla only); (3) Ledina*; (4) Malletina- (including 

 Tlii(l(trt<t); (5) Lyrodesmatinse (for ancient fossil forms like Lyrortesma,, 

 but including' the living genus Plmxcolitx or tiilicttld). An additional 

 group was formed for some other doubtful fossil genera. The second 

 of these groups is not well founded, for San-pta agrees closely with 

 Yoldi, except ifi the alleged absence of a pallial sinus, but its gaping 

 shell indicates a. siphon tube. The fourth should not include Tiiirtaria, 

 which lacks the pallial sinus and siphon tubes characteristic of the 

 rest of the group and should be taken as the type of a new subfamily. 

 The fifth should not include Phaseolux, which differs widely from the 

 fossil forms and belongs in the Ledina*. The other genera of this 

 group are referred to Trigouiadoi by other authors, and that would 

 seem to be a more correct arrangement. 



Family NUCULID.E. 



NUCULINA d'Orbigiiy, 1845. 



Pleurodon. S. WOOD, 1840. 



Nucnlina D'ORBIGNY, 1845. 



NudiieUa S. WOOD, 1848. 



yncnHiia VEKKILI. and BUSH, Amer. Jonrn. Soi., III, pp. 53, 59, January, 18!>7. 



We have included yuculhta in the ^uculida- with some doubt, 

 because authors differ as to its structure. Some state that its liga- 

 ment is wholly external and others to the contrary. Fischer places it 

 in the Arcidre, near Limopsis, but it has no ligauiental area. 



Mr.Dall kindly forwarded to us excellent unpublished figures of two 

 American species of this genus. In these the thickened ligament is 

 external to the hinge-plate, on the end of the shell which is destitute 

 of a lateral tooth, and is the shorter (posterior?). The beaks turn 

 toward this end. Mr. Ball states that the shells are not distinctly 

 nacreous within. 



The following are some of the known species: 



N. miliaris Ueshayes; N. ovalis S. Wood; N. calabra Seguenza, 

 fossil; N. munita Carpenter, from the Catalin Islands; T. xntcntn A. 

 Adams, from Korean Straits; N. add nisi Ball, from Florida and the 

 West Indies. 



NUCULA Lamarck, 1799. 



Niicula LAMARCK, Prodrome d'uue Xouv. <!. des ( 'oipiillrs, p. S7, \<>. lot, ITllM. 

 Nttuiilaita LINK, Jiesdir. Ifost. Saminl., p. 155, 1807 (not of Adams, 1858, nor of 



Harris, 1897). 

 Nucitla BALL, Bull. Mus. C'omp. Zool., XII, p. 245, 1886. 



Type. Nucula nucleus Lamarck. 



Nuculana (Link) was an exact synonym or variant of \ucula, of 

 earlier date, as the description plainly shows. There was, therefore, 



