SYSTEMATIC DESCRIPTIONS — SPAT ANGINA. 87 



Brissus brissus (Leske). 



Spatangus brissus Leske, 1778, Add. ad Klein, pp. xx, 182. 

 Spatangus columbaris Lamarck, 1816, Anim. sans Vert., vol 3, p. 30. 



Brissus columbaris A. Agassiz, 1883, Mem. Mus. Comp. Zool., vol. 10, No. I, p. 93. Cotteau, 

 1897, Bol. Com. Mapa Geol. Espana, vol. 22, p. 77, plate 26, figs. 1 to 3. 



I have not seen fossil material of this species. Cotteau, in his Spanish 

 paper, describes the species and copies some old figures of a specimen 

 from Cuba, but without detailed locality. According to Cotteau, this 

 species probably also occurs in Guadeloupe. Indeed, A. Agassiz lists 

 the species as from the Pliocene of Guadeloupe. It appears evident, 

 from his resorting to a copy for an illustration, that Cotteau had no 

 material himself. 



Brissus exiguus Cotteau. 



(Plate 15, Figures 2 to 4.) 



Brissus dimidialus Guppy (non Agassiz), 1866, Quart. Jour. Geol. Soc. London, vol. 22, p. 301. 

 Brissus exiguus Cotteau, 1875, Kongl. Sven. Vet. Akad. Handl., vol. 13, No. 6, p. 35, plate 6, 



figs. 16 to 18. Guppy, 1882, Scientific Assoc. Trinidad, Proc, part 12, p. 198; 



1911, Quart. Jour. Geol. Soc. London, vol. 67, p. 685. 



The following is an extract from the original description- of this species : 



Species of very small size, elongate, narrow and rounded anteriorly, 

 subtruncate posteriorly. Upper face swollen, subcarinate posteriorly. 

 Lower face regularly elevated, depressed in front of the peristome. Apical 

 disk very excentric anteriorly. Anterior furrow wholly wanting, anterior 

 ambulacrum III straight, elongate, narrow, with large tubercles; pores are 

 widely separated and scarcely visible. The paired ambulacra are wide, 

 subflexuous, very unequal; the anterior pair II and IV are nearly trans- 

 verse, a little rounded at the ends, moderately excavated; the posterior 

 pair I and V are longer, straighter, a little deeper and much less divergent. 

 The poriferous areas are wide, with elongate, narrow, equal pores in the two 

 half-areas approaching one another so closely as to leave no interporiferous 

 area. Tubercles are relatively well developed dorsally on the border of 

 ambulacrum III and near the apical disk on the interambulacral areas; 

 fine and crowded on the marginal region ; larger and more widely separated 

 ventrally. Peristome semicircular, very excentric anteriorly. The apical 

 disk is small, compact, granular, with only 3 genital pores in the specimen 

 in hand; the genital pore of the madreporite appears to be atrophied. 

 Peripetalous fasciole subflexuous, not limiting the large tubercles of the 

 dorsal side. 



Height 11 mm., length 19 mm., width estimated at 13 mm. It is 

 estimated because one side is crushed and therefore an exact measure- 

 ment of the width can not be made. 



This beautifully preserved specimen in Washington is the only one 

 that Cotteau had, as he states. It is therefore a holotype and the original 

 of his figures. The ambulacral petals II and IV, which measure 5 mm. in 

 length each, are at right angles to the long axis and, except for the slight 

 forward curvature, are almost in a straight line, making practically an 

 angle of 180° with each other; petals I and V are a little longer, measur- 

 ing 7 mm. each; they extend back, forming an acute angle of about 40° 

 posteriorly. The absence of a genital pore in the madreporite, as noted 



