CHELIDONOPStS 1367 



The following- are unfigured Mutelas : 

 Mutela hivigerina Bourguignat, Un. and Ir., 1886, p. 26. Lake 



Tanganyika. 

 Miitela moinrti IjOurgutgnat, IJn. and Ir., 1886, p. 2y. Lake 



Tanganyika. 

 Iridina zveluitscJiii Mokeli-T, Voy. de x\ngola,, 1868, p. — . 



Genus CHELIDONOPSIS Ancey, 1887. 



Chelidomira Rochebrune, S. B. Nat. Fr., 1886, p. 3. 

 Chclidonopsis Ancky, Conch. Exchange, \l, 1887, p. 22. — Ger- 

 main, Arch. Zool. Exp. et Gen., (5), L 1909, p. 4. 

 Shell elongated, thin, narrowed in front, gaping on the an- 

 terior basal part and winged on the front dorsal portion, round- 

 ed behind, with a pinched-up posterior ridge which develops 

 into an open or closed tube near its hinder part ; the shell end- 

 ing in a diamond-shaped gap ; epidermis shining, slightly, con- 

 centrically grooved ; hinge-line narrow, straight, with faint 

 vestiges of denticles ; a deep furrow inside marking the posi- 

 tion of the posterior ridge ; muscle scars faint ; nacre brilliant, 

 iridescent. 



Type, Chelidoniira arietina Rochebrune. 

 Germain, (1. c), has published an exhaustive study of the 

 anatomy of this curious group and summarizes his conclu- 

 sions as follows : "The Chelinodopses possess the typical or- 

 ganization of the Mntelidcr, slightly modified by secondary 

 adaptations due to the modus znvendi peculiar to these animals. 

 These secondary characters are the presence of two triangular, 

 posterior prolongations of the mantle, which line the interior 

 of the aliform extensions of the posterior region ; the exist- 

 ence of a narrow projection of the mantle in consequence of 

 the deep carinas of the posterior region ; the more accentuated 

 individualization of the anal and branchial siphons, which are 

 comipletely united their entire length, while they are generally 

 free at their posterior extremity in the MutcUe and Mutelince. 

 The study of the anatomy thus corroiborates the results ob- 

 tained by the study of the shell and we are to consider the Che- 

 linodopses as much evolved Mutelce." 



