BIIIAXG TILL K. SV. VET.-AKAD. HANDL. BAND 13. AFD. IV. X:0 10. 13 



sisting of numerous species of Echinidge, Spatangidse, Cly- 

 peastrid^, mostly of tertiary origin, many of which attain 

 considerable dimensions. In some minor details it recalls the 

 otherwise dissimilar Clypeastridse ; from the Cassidulidie and 

 Ecliinoneidff! it difFers Avidely. In tlic old group of tlie Echi- 

 noconida; alone it is admittcd, and there it approaches the 

 genus Pygaster, seen already in Liassic time, vigorously deve- 

 loped during Jurassic ages, deoreasing, it will appear, in the 

 Cretaceous, and as yot imrecorded from the Tertiary period. 

 Bnt characters are not wanting by which it deviates from that 

 ancient type, and they are importaut enough to lead to the 

 creation of a separate geniis. For this a name is to be de- 

 vised, and following the train of thoiight suggested by a cer- 

 tain family likeness I propose the patronymic one of 



PYGASTRIDES Lov. 



Genus Echinoconidarum. 



Periproctium dorsale, posticum. Assula? ambulacrales om- 

 nes simplices, primis latis, uniporis, auriculas sustinentibus 

 longitudinales, separatas; zonis pororum simplicibus, directis. 

 Spha^ridia singula. Assula? interradiales peristomatis singulas^ 

 latEe. Tubercula perforata, crenulata, priraariis majusculis. Epi- 

 stroma luxurians. 



Pygrastrides relictiis Lov. 

 1874. Pygaster relictus Lov. Etudes s. 1. Echin., p. 69, nota. 



Habitat in Mari CaribbaBO, juxta »Virgin Islands», profun- 

 ditate 200—300 orgyarum; A. GoÉS. 



