THE FAMILY ASTEORHIZID^ 111 



tions, but with one end closed, as in Jaculella and 

 Hyperauuiiina, whilst some sinuous and branching 

 forms are represented by BJiizaHniiiiia. 



The typical Asfj-orJii.m has a test composed of 

 fine sand and mud ; the primordial portion of the 

 test is the central swollen part,, from which starts 

 a series of radiating tubes. Modifications of this 

 type form are found in DendrojjJirya, the tubes of 

 which are usually compressed and irregular. 



Syringammina is a complicated radial growth of 

 astrorhizid tubes, the whole test having a spherical 

 contour. 



A ramifying network of finely arenaceous tubes 

 adherent to shells and alg<;e is represented in the 

 genus Sagenina. In Bliahdaimnina the test is 

 tubular and radial, the arms being limited in number 

 to three, four, or live rays, which are generally 

 straight. The structure of the test is usually 

 coarsely arenaceous. Marsipella is another tubular 

 form, with apertures at both ends ; and its test is 

 normally composed of short sponge spicules, grouped 

 in little bunches as it were side by "side. 



Botellina is distinguished from some forms of 

 Hyjjerammiiia having regular or straight tubes, by 

 the peculiar inner structure of the test, which in 

 the former genus is irregularly divided by partitions, 

 so that the interior is labyrinthic. 



The recent genus Ascliemonella is singular in 

 having a somewhat different structure from the rest 

 of the AsTRORHiziD.E, for in this genus we have indi- 

 cations of a partially septate test, connecting it with 



