ART. 4 SPONGES OF CALIFORNIA DB LAUBENFELS 33 



lected from the same general locality and depth, in May, 1929, are 

 given under Remarks below. 



Descpiptian. — Shape, various (see discussion below). Size, up 

 to 2 cm thick, 20 cm in diameter. Consistency, fragile, friable. 

 Color in life and when preserved, pale drab. Oscules, skeletal open- 

 ings, 1 to 2 mm in diameter, and about 2 to 10 to the square centi- 

 meter. They are covered with a fenestrated membrane packed with 

 asters, having roundish apertures about 0.4 mm in diameter. They 

 open from subdermal spaces upwards of 1.2 mm in depth into which 

 open numerous afferent pores usually 0.2 to 0.7 mm in diameter. Pores, 

 skeletal openings, about 1 mm in diameter, covered witli a fenestrated 

 membrane having apertures 0.1 to 0.2 mm in diameter. The skele- 

 tal pores and oscules are roughly outlined (surrounded) by the 

 cladomes of the ectosomal tetr axons. Surface, superficially smooth, 

 with scattered projecting spicules a few millimeters high. 



Ectosomal specialization: A dermal membrane about 40/a thick, 

 very fragile and delicate; it contains abundant asters. Endosomal 

 structure " crumb-of -bread," with fascicular tracts of oxeas, others 

 scattered, and abundant scattered calthrops. Many calthrops have 

 three of their rays directly beneath the dermis and parallel to it. 

 Principal tracts (found only running lengthwise of lamellate forms), 

 lOO/x to 200/i in diameter. 



Principal spicules, calthrops (fig. 13, A, B^ G) ; size of rays, 50/x 

 by 450/i to 70/x by 650/a. Interstitial spicules, oxeas, sometimes styles 

 (fig. 13, Z>, E^ F) ; size, about 65/x by 3,T00;n. Coronal spicules, oxeas 

 (not figured) ; size, 15/a to 30/x by 17,000/i,. First microscleres, abun- 

 dant plesiasters (fig. 13, /, K) ; size of rays, about 6/i to 8ju, long, 

 greatest diameter 14/x to 18/i,. Some have so few rays that they are 

 microcalthrops. Second microscleres, rare spirasters or metasters 

 (fig. 13, Z, M, N) ; length, 10/a to 13/*; rays about 3/* long. Third 

 microscleres, toxas (fig. 13, /) ; length, about 80|U,; located throughout 

 the sponge. These toxas are, of course, quite probably foreign, yet 

 they are found in every part of the holotype that I have examined. 

 One can hardly believe them proper, yet their occurrence deserves 

 mention. Fourth microscleres, microxeas, 4//, by 170/* to 5ju, by 270/i 

 (fig. 13, G^ H). As many Poecillastras have spined microxea, I 

 made an especial examination of these. With very high magnifica- 

 tion (more than 1,000 diameters), the surface of these spicules was 

 seen to very minutely roughened. As such roughening might be 

 detected on almost any spicule by sufficient magnification, it is ques- 

 tionable how much taxonomic value it has. These sj)icules are rather 

 evenly distributed throughout the sponge. 



Remarks. — The holotype is of the usual form of Poecillastra., with 

 spiculation not greatly differing from P. compressa, P. schultzei^ and 

 107704—32 3 



