100 P. KITTON ON DIATOMACEOUS DEPOSITS FROM JUTLAND. 



Dr. Heiberg, in the above-mentioned work, proposes a new 

 family, based on the genus Hemianlus of Professor Ehrenberg, a 

 genus well represented in the Barbadoes deposits. The species of 

 this genus bear a superficial resemblance to the genus Biddulphia, 

 but ajiproach nearer to some forms hitherto considered as Trice- 

 ratia. The following is Dr. Heiberg's synopsis of the family: — 



HEMIAULID.E HEIBERG. 



Frustules uniform, front and side views always symmetrical, 

 nearly rectangular in front view, with long horn-like (hyanes- 

 tillede) processes terminating in one or two straight or inclined 

 spines, the processes straight on the outer margin, forming a right 

 angle with the base of the valve (en ret Yinkel mid Skallens 

 Grundflage). Sculpture consists of larger or smaller punctas ; 

 variously arranged costse are sometimes present ; markings of 

 connecting zone (Bindehinden) less conspicuous. 



Tribus I. — Hemiaulidce genuince. 

 Outline of side and front views symmetrical, both in longitu- 

 dinal and transverse axes, or if more than two axes symmetrical 

 with all of them. 



Genus 1. Hemianlus. Ehr. 

 Outline of valve elliptical (lanceolate oval), produced at the 

 longer axes into horn-like processes, the points of which are pro- 

 Tided with a spine (een Torn). 



.Genus 2. Trinacria. Heiberg. 

 Outline of valve with three* equal angles (with axes of equal 

 value), front view of frustule with three horn-like processes, each 

 terminating in two spines. 



Genus 3. Solium. Heiberg. 

 Outline of valve regularly quadraticf or rhomboid, frustules in 

 front view with horn-like processes at the corners, and terminating 

 with two spines. 



Tribus II. — Hemiaulidce cuneatw. 

 Outline of valve oval (asgdannet), front view wedge-shaped, 

 frustule only symmetrical in the long diameter. 



Genus 4. Corinna. 

 Outline of valve regularly oval, with two horn-like unequal 



* This character of the Author must be enlarged if of any generic or specific 

 value, as Trinacria regina occurs with four sides. 



t The preceding remarks apply to this genus. In the Fuur material we 

 find Solium exsculptum with five angles. For specimens of this form I am 

 indebted to G. M. Brown, Esq., of Liverpool. 



