Smithsonian miscellaneous collections . rly common from eastern Canada to Greenlandand over to the coast of Norway. Needless to say, the identification, 6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 121 being based only upon fragments, cannot be at all certain. The genusPellina, however, is indicated, and the species sitiens is the only oneto be expected. Family Myxillidae Genus MYXILLA Schmidt MYXILLA INCRUSTANS (Johnston) Lundbeck In July and August 1951 this species appeared in our dredges onlya few times, from about three localities, all upward of 10 kilometers( miles) west of Point Barr
Smithsonian miscellaneous collections . rly common from eastern Canada to Greenlandand over to the coast of Norway. Needless to say, the identification, 6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 121 being based only upon fragments, cannot be at all certain. The genusPellina, however, is indicated, and the species sitiens is the only oneto be expected. Family Myxillidae Genus MYXILLA Schmidt MYXILLA INCRUSTANS (Johnston) Lundbeck In July and August 1951 this species appeared in our dredges onlya few times, from about three localities, all upward of 10 kilometers( miles) west of Point Barrow, at depths of 50 meters or more,but each time it was abundant, practically filling the dredge. M. in-crustans has also been dredged in quantity by G. E. MacGinitie onfour occasions in September and October 1948 and 1949, at 33 to 100meters (108-328 feet) from mud and stone, gravel, and rock bottom,4 to miles ( km.) off the Point Barrow base. The followingdescription is based on July 29, 1951, material ( No. 23217).. Fig. 3.—Spicules of Myxilla incnistans, X 210. A. Dermal tornote;B, acanthostyle; C, sigma; D, isochelas. Camera lucida drawing. The shape is irregularly massive, up to 16 cm. in diameter, colordrab, like nearly all Arctic sponges, consistency very slimy, but withlittle or no odor. The surface is smooth, with indications of abundantbut quickly closed pores. The oscules are regularly 2 mm. in diameter,not raised, rather numerous. There is a definite, separable dermis overan endosome characterized by small (i mm. or less) scattered cavities. The dermal spicules, chiefly tangentially placed, are smooth, hastatetornotes, ends sometimes microspined, size about 8 by 180 endosomal spicules are acanthostyles, in log cabin reticulation,size about 17 by 260 microns. It is probable that this spicule arrange-ment represents an exaggerated development of echinating spicules,with a relative suppression of coring spicules. The microscleres aresig
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