72 CxOÉS, RETICULARIAN RHIZOPODA OF THE CARIBBEAN SEA. 



Textularia sagittula Defr. 



Tab. IV, figg. 133—158. 



The species of Textulariaä are not less difficult to define within proper boundaries 

 than are Nodosarinse. It is obvious that inany gradations in the flatness or in the dis- 

 tention of the chambers will make the whole liable to numberless variations, from a 

 conipressed lanceolate to a quite conical shape with either straight or sinuous margins 

 and contours. 



The shellsubstance is also variable in character being sometimes more translucent 

 and glossy, but it is usually agglutinated of calcareous or siliceous debris. In the 

 whole range of known Textularia^ forms it is therefore not easy to distinguish besides 

 the Gaudryina- and Verneuilina-forms more than 3 or 4 species; that is to say: 



1. Textularia sagittula Defr. or agglutinans d'Orb., including such forms as: 

 Textul. pygm£ea, Mari?e, carinata, cuneiformis, Baudouiana, conica, caribsea, 

 aciculata, agglutinans, Candeiana etc. d'Orb. and a long list of names from 

 Reuss and others. 



2. Textularia gibbosa d'Orb. should be another but, it is a very ill defined 

 species; its chambers being more inflated. 



3. A thivd species is Textularia trochus d'Orb.; this has some tendency to be- 

 come »Cuneoline». 



4. The fourth species is Textularia pennatula Batsch., apparently representing an 

 intermediate form between the textularioid Bulimina? and the real Textularia. 



All these species have their respective BigenerinEe forms. 



Whether »Gaudryina» and »Verneuilina» are to be considered as »varieties», or 

 »species», is a question that we are not yet prepared to settle, as our collections are 

 wanting in intermediate forms. 



The transverse section of our form varies from narrow oval or pointed elliptical 

 to nearly orbiculnr. The more »sagittular» form exhibits often raised bands along the 

 sutures. In older speciraens the surface is more chalky and uneven. All forms that 

 we have met with are agglutinant; the shell being compactly built up of very fine 

 chalk-debris and dust. Very young ones are semitransparent, presenting a deep brown 

 tint in transraitted light; the fine granular texture of the shell concealing the pores. 

 It appears from many instances in our collection, that whenever the Textularia-stadium 

 becomes more developed, the Nodosarina growth is reduced to only one or two cham- 

 bers; and on the other hand, whenever the Nodosarina-stadium has a high development 

 the textularia-part is found to be stunted and often reduced to a few chambers. These 

 fluctuations of development give rise to a number of varietal Bigenerina-forms. All 

 our forms are composed solely of calcareous raatter. 



Figg. 133 — 136: intermediate form between d'Orbigny's Textul. agglutinans and 

 Textul. sagittula, and provided with one »Nodosarina»-chaniber, the first step towards 

 forma »Bigenerina». 



Figg. 137 — 139: the same more flattened and sagittuhi-Vike. 



