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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 81 



Remarks. — The most abundant spicules seem to be the oxeas, 

 which are commonly about 600/i, to 800/a long but sometimes more 

 than 1 mm. They are typically nearly tangential, but not quite, the 

 distal fourth or third hispidating the surface. Smaller ones occur 

 among them. The triradiates are between them and the gastral 

 layer. The gastral (or cloacal) layer is packed with autogastral 

 quadriradiates, the projecting ray comparatively short. The choano- 

 cytes are arranged on this inner surface only, as typical of ascons, 

 and their nuclei are centrally located within the mass of the cell. 



This species comes very close to the genus Ascute^ which has 

 the large oxea entirely embedded within the flesh. Its genotype, 

 A. uteoides Dendy (1893, p. 178), from Australia, has besides this 

 difference the further ones of lacking triradiates and having oxeas 



Figure 4. — Leucosolenia nautilia de Laubenfels : Extremes of 

 size for the small oxeas (V, E) and average sizes for the 

 other spicule sorts {A, B, C), X300 



twice as thick though not much longer; nevertheless, I regard it 

 as fairly closely related to nautilia., as other items are very similar. 

 There is some possibility that the numerous differences from Leuco- 

 solenia eleanor^ the common local intertidal member of this genus 

 (p. 8), may be accounted for by the peculiar ecological placement 

 of nautilia. There seems to be no other record of calcareous sponges 

 fouling boat bottoms. Neither mussels nor sponges occur at all 

 commonly on the bottoms of the fishing boats around Monterey 

 Bay. 



Family SYCETTIDAE Dendy 



Genus SYCON Risso 



SYCON COACTUM (Urban) 



Sycandra coacta Urban, 1905, p. 55. 



Sycon coaotum Dendy and Row, 1913, p. 745. 



Holotype. — In the possession of Prof. F. Urban, Marienbad, 

 Czechoslovakia. 



