424 DESCHiPTiow OF \^Polygastrica' 



Staitroneis Sigma. — Has the form and size of Kavicida Sigma, 

 but ^vitll au apparent double central exj)anded umbilicus. Length 

 1 -240th. Richmond, Virginia. 



S. augusfn. — Discovered by Ehrenberg, in earth from Siberia. 



S. Aflantica. — Small ; lanceolate dorsally, with obtuse aj^ices ; 

 linear laterally. Approaches S. ainphileptus. Var. of S. amphileptus of 

 Chili; more obtuse. Length 1-11 52nd. In pumice from the 

 Island of Ascension. 



S. lanceolata, (Kiitz.) — Slender, lanceolate, with subacute apices, 

 which are also rather produced and acuminate. Length 1-1 80th to 

 l-160th. Falaise. 



S. exiJis. — Veiy small, elliptic-lanceolate ; shortly rosti'ate. 

 Length 1 -2400th. In fr-esh-water, Trinidad. 



S. amphicephala. — Linear-oblong, apices produced, rostrate and 

 capitate. Nordhausen. 



S. injlata. — Oblong, widely expanded at the centre, and the two 

 ends thus having two constrictions j ends widely rounded, truncate. 

 Length l-480th to l-428th. Trinidad. 



S. ventricosa. — Very small, especially in the middle, and inflated ; 

 capitate twice constricted ; umbilicus transverse. Length 1-1 320th. 

 Nordhausen. 



S. pumila. — Elliptic-lanceolate, acute, margin punctate, striate ; 

 laterally oblong, widely truncate. Length l-1440th to 1 -1080th. 

 Christiana. 



Kiitzing does not make a generic distinction between Stauroneis 

 and Stauropiera ; hence the present, and the following species, derived 

 from his great work, are, as understood by Ehrenberg, Stauroptera. 



S. Aehnanthes = Stauroptera Achnanthes (Ehr.) 



S. aspera = Stauroptera aspera (Ehr.) 



S. Isostauron = Stauroptera isostauron (Ehr.) 



^.parva = Stauroptera parva (Ehr.) 



S, scalaris = Stauroptera scalaris (Ehr.) 



8. punctata. — Small, broadly lanceolate, apices produced, rostrate j 

 transverse strite j^unctate Fossil, San Eiore. 



S. microstauron = Stauroptera microstauron Ehr.) 



S. (?) gihla = Stauroptera (?) gihha (Ehr,) 



S. Legumen = Stauroptera Legumen (Ehr.) 



