REPORT ON THE ECHIXOIDEA. 31 



closely allied to the present Mediterranean species Schizaster canaliferus ; under the name 

 of Echinus dux, a species which has aU the facies of Sphwrechinus with the structure of 

 the poriferous zone of Echinus proper; also Echinocyamus, which varies to such an extent 

 that it is well-nigh impossible to separate many of the more recent Tertiary forms from 

 the species still living. The species described by Laube is remarkable for showing in so 

 large a species the sculpture in the line of the horizontal sutures characteristic of the young 

 stages of Ecliinocyamus such as I have figured in the Ee vision of the Echini, pi. xiii., 

 while the presence of such a tj-pe as Amphiope elUptica (Echinodiscus) shows evidently the 

 former extension of the genus far to the eastward of its present range ; and the existence 

 of species of Schizaster like Schizaster leithanus (Laube), with very decided Hemiaster 

 affinities, enable us readily to see how Hemiaster may gradually have been modified into 

 the typical Schizaster of the present day. Spatangus austriacus seems from Laube's 

 figures to be more closely allied to Spatangus raschi than to Spatangus purpureus, 

 while Brissomorpha is evidently an entirely difierent type, which unites, like many of the 

 deep-sea Spatangoids lately discovered, characteristic features of several genera. It has 

 the greatly developed posterior interambulacrum forming a regular beak covering the anal 

 system somewhat as we find it iu Echinocrepis, but it has the labiate actinostome of 

 Brissus, with the outline from above of Echinolampas ; its representative in the 

 present day is Nacopatagus, with which it is most closely allied. Manzoni and Mazetti 

 have figured and described in the Atti Soc. Tosc. Sc. Nat., iii. pi. xix. fig. 2, under 

 the name of Heterobrissus, one of the Spatangoids with ambulacra flush with the test 

 (but with few pores), which seems to be more closely related to some of the abyssal 

 genera such as Nacopatagus than any other; and seems to indicate, from the structure 

 of its petals and the consequent long line of simple pores forming the ambulacral 

 areas, how the present genera, that is, the whole group of the Pourtalesise wdth simple 

 pores, originated and came to persist, retaining the embryonic tyj^e through which 

 all Spatangoids primarily pass, the apetaloid state, which is but slightly advanced in 

 Heterohriss^is. 



When we compare the Nummulitic species of Echinids with those now existing either 

 in the littoral, or in the continental and oceanic zones of the Indo-Pacific region, we 

 find that the generic types have continued to the present day, and many species will 

 undoubtedly prove to be identical, on close comparison of more extensive series of the 

 large number of Temnopleuridse which characterised the Indian Seas of the Tertiary 

 beds with those of the present day, as well as with the species of Maretia, Brissopsis, 

 Hemiaster, Temnechinus, Echinanthus, Echinolampas, and other Cassiduloids, which 

 have been figured by Herklots, D'Archiac and Haime. 



From the excellent descriptions of the Australian Tertiary Echinids of Duncan, of 

 Laube, and of Tate, we cannot fail to be struck with the existence in the Austrahan 

 Tertiaries of the genera Eupatagus, Lovenia, Arachnoides, Echi)iohrissus, Fihularia, 



