1616 THE VOYAGE OF H.M.S. CHALLENGER. 



One genus only, and two species, of Aulosphserida have been hitherto known, having 

 been discovered by me in 1859 at Messina, and described in my Monograph in 1862 

 as Aulosphcera trigonopu and Aulosphcera elegantissima (loc. cit., p. 357, Taf. x. figs. 4, 5 ; 

 Taf. xi. figs. 5, 6). The characteristic structure of their central capsule, as true 

 TRIPYLEA, was afterwards, in 1879, described more accurately by Richard Hertwig 

 (Organism, d. Radiol., p. 90, Taf. x. figs. 2, 8, 14). The rich collection of the Challenger 

 has demonstrated that the Aulosphserida belong to the most common and most widely 

 distributed PH^EODARIA; many of them are distinguished by the admirable elegance and 

 astonishing regularity of their large and delicate shell. Nine genera and fifty-six species 

 of this great family are described in the following pages, which, however, may represent 

 only a small part of the numerous forms which are found on the surface as well as in 

 different depths of all oceans and in all zones. 



The shell is in the great majority of Aulosphserida a regular sphere or an endospherical 

 polyhedron. Two genera only, both rather rare, exhibit a different monaxonial form, one 

 vertical main axis being developed either more or less than all the other ones of the 

 sphere : Aulatractus is spindle-shaped or ellipsoidal, with prolonged main axis ; 

 Aulophacus is lenticular or discoidal, with shortened main axis. The former may be 

 compared to the Prunoidea, the latter to the Disco idea, in opposition to the 

 common regular Sphseroidea. The size of the lattice-shell is very considerable in all 

 Aulosphserida, its diameter varying usually between 1 and 3 mm., often it amounts 

 to 4 or 5 mm.; very rarely the diameter is more than 5 or less than 1 mm. The 

 largest form observed is the spindle-shaped Aulatractus, in which the vertical prolonged 

 main axis attains 6 to 10 mm., the horizontal equatorial axis 3 to 5 mm. 



The network of the lattice-shell exhibits in the Aulosphserida two different types, 

 according to which we distinguish two different subfamilies : Aularida and Aulonida ; 

 the former are much more common and richer in remarkable forms than the latter. The 

 meshes of the network are in the Aularida constantly triangular, regular or subregular, 

 and very similar to those of the Sagosphaerida ; at each nodal point six tangential tubes 

 are usually united, so that the network may be regarded also as composed of regular 

 hexagonal meshes, each of which is divided into six smaller triangular meshes (PI. 109, 

 figs. 1, 3, 5). The second subfamily, the Aulonida, are much rarer than the former, and 

 are distinguished by the polygonal meshes of the network ; these are usually more or less 

 irregular, pentagonal and hexagonal intermingled, more rarely tetragonal, heptagonal, or 

 octagonal ; usually three or four, rarely five or more tangential tubes are united at each 

 nodal point (PI. Ill, figs. 1, 3). The size of the meshes is very considerable, and agrees 

 with that of the Sagosphserida ; their diameter being usually between O'l and 0'3, rarely 

 less or more. 



The hollow tubes which compose the loose network are usually cylindrical, straight 

 or slightly curved, smooth (PI. Ill, fig. 2), more rarely somewhat spinulate (PI. 109, 



