. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. 140 PORIFERA. teeth, and 011 either side a narrow ala. The alae continue along the shaft, and in the middle they are connected by a quite narrow rim; thus there is no free middle part of the shaft, but only an incision in the rim running on either side. The ancorse are very varying in size, their length is between 0-0157 and o-05mm, and the breadth is proportionately 0-004—o-oi8mm. The larger ancorse are most predominant. Developmental forms in different stages were seen. 2. Sigmata are of the common form and contort in
. The Danish Ingolf-Expedition. Scientific expeditions; Arctic Ocean. 140 PORIFERA. teeth, and 011 either side a narrow ala. The alae continue along the shaft, and in the middle they are connected by a quite narrow rim; thus there is no free middle part of the shaft, but only an incision in the rim running on either side. The ancorse are very varying in size, their length is between 0-0157 and o-05mm, and the breadth is proportionately 0-004—o-oi8mm. The larger ancorse are most predominant. Developmental forms in different stages were seen. 2. Sigmata are of the common form and contort in different degrees; their size is rather varying, the length from o-oi8—o-032nira, and the thickness from ca. o-ooii—o-oo2mm. Both forms of microsclera occur through the whole sponge and in no small numbers in the dermal membrane. Remarks: Of this species I have for comparison had a fragment of one of Schmidt's type specimens sent to me by Dr. Mark tanner-Turneretscher, and so I have been able to identify my species with certainty. It is also quite in conformity to Lieberkiihn's description and figures ; especiallv the figure of the acanthostyli is exceedingly characteristic. On the other hand neither Lieberkiihn nor Schmidt mentions the pluripointed ends of the tornotes, but they must also be seen under very high magnifying powers to be made out distinctly. In Schmidt's type specimen the megasclera are a little smaller than in my specimens; thus the styli have an average length of o-i6mm, and do not exceed o-iyS"11", and the average length of the tornotes is o-i5mra, and they do not exceed ^ Schmidt describes later, under the M. tridens established by him in 1864 , the three- pointed tornotes very minutely, and compares very appropriately the form of their ends to the head of an Ascaris. In 1868 he (Die Spong. der Kiist von Algier, 27) joins, and, no doubt, correctly, this species to M. rosacea. When Vosmaer 1. c. further refers Schmidt's M. fasc
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