298 PROCEEDINGS OF THE ACADEMY OF [1885. 



one of the other groups. We do not except the calicine pores or 

 the pectinated rhombs, -which are regarded as characteristic of 

 the Cystids, nor the lamellar tubes beneath the ambulacra, which 

 were thought to be restricted to the Blastoids. Even jointed arms 

 occur in many Cystids, and in some of them they are connected 

 with the radials in a similar manner as in the Crinoidea. 



We <lo not wish to enter upon a discussion of the structural 

 peculiarities of the Cj'stidea and Blastoidea, and, if we allude to 

 them here, it is onty to illustrate their close affinities with one 

 another, and with the Palaeocrinoidea. Asteroblastus, judging 

 from thecatyx, is a Cystid, but it has Blastoid ambulacra, 

 Blastoid pinnules, associated with ambulacral and calicine pores. 

 The same structure occurs in (?) Agelacrinus Pusirewskii Hof- 

 mann. On the other hand, the Blastoid genus Godaster has 

 neither spiracles nor ambulacral pores ; its hydrospires open out 

 like those of certain Cystidca, and they do not underlie the 

 ambulacra, but are placed alongside of them. Godaster was 

 referred b} r Billings and Zittel to the Cystidea, but is now 

 generally recognized as a Blastoid. Stephanocrinus has been 

 variously described as a Crinoid, Blastoid and Cystid. As 

 admitted b} r Carpenter, it has probably no hydrospires, and so 

 far as known no calicine pores nor pectinated rhombs, but it 

 possesses long Crinoid-like brachial appendages. Caryocrinus, 

 which has been very generally regarded as a Cystid, has seg- 

 mented pinnule-bearing arms like a Crinoid, and these are at- 

 tached to the radials, but it has calicine pores, and numerous 

 hydrospires along the inner floor of the calyx. Porocrinus has a 

 calyx and arms like a Cyathocrinoid, but calicine pores like a 

 Cystid. J/i/Ijocystites was described by Wetkerby as a Cystid ; 

 by Carpenter as a transition form between Crinoids and Blastoids, 

 but nearer the latter ; while we consider it a Crinoid. Its arm 

 structure is that of a Cystid, hut it has apparently neither calicine 

 pores, rhombs, nor lamellar tubes. The Crotalocrinidre and Euca- 

 Lyptocrinidse probably have hydrospires within the calyx, Cupres- 

 socriim.< and Symbathocrinus probably li3 T drospires underneath the 

 ambulacra, and both have segmented arms. 



These few examples, to which others might be added, will 

 sufficiently show that neither the Blastoidea and Cystidea, nor 

 the Crinoidea propel", form primary divisions like the Urchins, 

 Starfishes or Ophiurans, but constitute subordinate groups of the 



