268 



The ooecia (ligs. 1, .'{), wliich arc only I'orinccl hy a siiigk' zod'ciuni, are free 

 with llie exception of a small |)roxinial ])orlion of the endooa^cium formed by a 

 part of the zod'finm's fronlal wall dislal lo the aperUire. They are strongly arched, 

 not far from being globular and consist of two calcirietl layers of wliich the thick 

 ectooo'cium about the middle is provided with a low, girdle-shaped, proximally 

 convex impression covered by a chilinous jilale of the same form. \\'ilhin the 

 impression is seen an irregular series of mostly elongate pores separated by thick 

 cylindrical j)ilhirs. In the oa'cia-bearing zod-cia Ihc aperture is on each side pro- 

 vided with a small lounded protuberance (lig. li) dislally to the opercular ridge, 

 and the aperture of the od'cium can l)e closed i)y the operculum. 



Some colonies of this interesting species have been found incrusling shells at 

 Koh Kram, Siam, al a depth of iiO falh. I)y Dr. Th. Morlensen. 



Our Zoological Museum j)ossesses a small colony of another variety from Port 

 Phillip Heads, which has a nearly circular Tata-sha|)ed ancestrula, surrounded 

 by 12 marginal spines (tig. 4). The spines are not only much longer and stronger 

 than those in the variety from Siam but are divided into ca. S inlernodes. The 

 pore-bearing impression of the oa'ciuin is almost circular and within il is seen 

 a number of scattered pores. 



hi the form ligured bySavigny the Od'cium seems to be provided with scat- 

 tered pores, separated by a number of parallel longitudinal ridges. 



Before being able lo make a thorough examination of the present sj)ecies, I 

 have set forth the supposition in tlie niorpliological jiart that it might belong to 

 the Suborder Anaska and the reason for this supposition was cliiefly the lack of 

 the cross-bar in the vibracula together with a certain likeness to Mecjapora riinjens. 

 Later I have been able to examine some good colonies from Siam, and having 

 seen that the operculum is in connection with a compensation-sac I cannot longer 

 maintain this view, holding however at the same time that this genus has its 

 nearest relatives in the division Malacoxlcga. This appears not only from the lack 

 of the cross-bar, but also from the |)rescnce of marginal spines surrounding a 

 great deal of the calcilied frontal wall. \\'liile a great number of the Ascoplwnt 

 are provided with marginal sjjines surrounding the aiiter of the aperture (»oral 

 spines ), with the exception of Crepklacanihu we find marginal spines i)laced in 

 the circumference of the frontal wall only in the division Malacostega and only in a 

 few ancestruhv for instance in those of C.haperia spinosa^ and Microporclla riliala'- 

 do we find such spines together with a well-developed cry|)tocyst. Though llie sjie- 

 cies of the genus Meejapora are provided with a completely calcified frontal wall 



4,'), PI. 5, lig. :i. - 111, p. :VM, IM. l.'>, lig. (i. 



