Herbert L. Hawkins — On Lanier ia of Duncan. 199 



rounded at the lower end and narrowing gently upwards, usually 

 with obtuse angles at the upper corners due to the arising of a very 

 slight straight-edged internal front wall at the head. 



Ocecia abundant, rather fragile, consisting of gentle helmet-shaped 

 swellings with concave free edges. 



Avicularia witli very faint boundaries, rather modified from the 

 general Lesueuri-tj^e ; the infold of the side walls starts well above 

 the level of the top of the area and runs downwards with a straight 

 edge until it impinges slightly on the area close to its upper end and 

 forms the constricting prominence, which is thus exceptionally far up 

 the avicularium ; the cutting-back below is very slight, though 

 discernible ; upwards from the point where the infold starts the side 

 walls are straight and well marked and slope inwards to meet in an 

 acute angle, like roof timbers, so that the outline of the front wall is 

 that of a cross-section through a simple building ; the area is a narrow 

 ellipse, and, as indicated, the upper section of the area is very small, 

 the lower very large. 



This species is well represented at Trimingham. 



EXPLANATION OF PLATE VII. 

 (All figures x 12 diams.) 

 Figs. 1,2. MembraniporaGravensis. Zone ot M. co7--ang2iimnn, Gia-vesend. 

 ,, 3,4. M. cervicornis. Zone oi B. mticronata, 'Portsdo\Yn. 

 ,, 5, 7, 8. M. Sjparksi. Zone of A. quadratus, Portsdown. 

 Fig. 6. ,, Zone of A. quadratus, Hensting, Hants. 



,, 9. M. plicatella. Trimingham. 



Figs. 10,11. M. cedificata. Trimingham. 



III. — On Lanieria, Duncan, a kemarkable genus of the Holec- 



TYPOIDA ; WITH A PRELIMINARY NOTE ON THE TENDENCIES OF 



EcHiNoiD Evolution. 



By Herbert L. Hawkins, M.Sc; F.G.S., Lecturer in Geology, University 

 College, ;^eading. 



Contents. 



1. Historical. 



2. Eedescription of Lanieria lanieri. 



3. Description of CcBnholectypus cubes, n.sp. 



4. The family Lanieriinse, nov. 



5. The Biological Significance of the Lanieriinse. 



1. HiSTORICAL. 



SOME time after the year 1850 d'Orbigny recognized, among 

 a collection of fossils from Cuba, a species that he referred to 

 the genus Galerites under the name of G. lanieri. The description 

 and figures of the species were to have been included in vol. viii 

 of the Siatoria fisica, pol'itica y natural cle la isla de Cula, but the 

 part of that work that should have contained them seems not to 

 have been published. 



It was not until 1881 that Cotteau ("Description des Echinides 

 fossiles de Cuba," Mem. Soc. geol. Belg., vol. ix, p. 11, pi. i, 

 figs. 7-13) gave a description of the form. He used d'Orbigny's 



