CARADOCIAN CYSTIDEA FROM GIRVAN. 



429 



!j 270. To facilitate comparison, the accompan3'ing diagrams (text-figs. 36, 37) show 

 the terminology and symbols used by Dr Jaekel and myself respectively. 



left left right right 



anterior posterior posterior posterior anterior anterior 



IR R IR R IR K IR R IR R 



Circlet V 



IV 



L3 lA 



Deltoidea 



III 



10 





Basalia 



Text-fig. 36.— -Anaugemeut of plates in the sujjposed archetype of the Glyptocystidea. The numbers on the 

 plates were originally given by E. Forbes, and are those used in the present memoir. In the lettering 

 at tlie top, IR = interradiiis, R = radius. Plate 23 bears two pores (?hydropore and gonopore). The 

 notches in plates 15-19 represent the primitive position of five food-grooves. Between 7, 8, and 13 

 lies the anus. Pectinirhombs not shown. 



-a a A a 6 



Deltoidea 



Radio 



^Medio > lateralia 



Infra 



Basalia 



Text-fig. 37. — A precisely similar diagram to tig. 36, but with the numbers used by Jaekel. 

 from the posterior interradius and pass round the theca in a dextral direction. 



These start 



§ 271. From the real or supposed archetype of the Glyptocystidae I derived three 

 Subfamilies : Echinoencrininae, Callocystinae, and Glyptocystinae. Within these 

 Subfamilies I pointed out various groupings of genera that seemed to indicate a 

 phyletic connection. 



§ 272. The Echinoencrininae correspond exactly with Jaekel's Scoliocystidae, 

 and the only reason he did not take the obvious name Echinoencrinidae was his 

 objection to the length and etymology of the name Ecliinoencrhiites. But whereas 

 everyone could have understood at once what was meant by Echinoencrinidae, nobody 

 was familiar with the new, rare, and untypical genus Scoliocystis, a name, moreover, 

 liable to be confused with the earlier Scolocystis Gregory (1897). Therefore, while it 

 may be convenient to follow Dr Jaekel in according to this assemblage Family rank, 

 it seems advisable to give it the name Echinoencrinidae. For the present no Sub- 

 families have been or need be proposed. 



