64 DicTTospoNorD.?;. 



suiniait which appears to have been t)peii. The specimens vary between 23 

 and 30 mm. in height, and from 14 to 17 mm. in Avidth. 



" The sponge -wall appears to have been smooth and even ; the lai'ger 

 areas of the rectangular mesh-work are marked out by more prominent, vertical 

 and transverse raised lines, and vary from 1.5 to 3 mm. in length, and these 

 are subdivided by finer lines into smaller squares, the sides of which are 

 about .75 mm. in length. In some cases the stronger lines forming the larger 

 squares are nearly parallel from the base to the summit, whilst in others they 

 converije to each other towards the base. 



" No spicular structure whatever has been preserved in any of the speci- 

 mens yet discovered, which are merely casts in a matrix of micaceous sandstone. 



No structure can be detected in the interior of the 

 specimens." (Hinde, op. cit. 1888.) 



The foregoing description was based upon McCoy's 



original sjjecimens and his figures are here reproduced. 



These show an obscurely piismatic form which is not 



.„ „ ^ . « . reproduced in the figures of the sijecies given by 



FiouRE 10. McCoy's Sgurc:i of £ O 1 O J 



TetragonisDanbyi. IIiNDE uor mcutloned lu hls description. This species, 



a fossil of rare occurrence, is the oldest known representative of the 



DlCTYOSPONGID^. 



Localities. From the upper Ludlow rocks at Brigsteer, Benson, Under- 

 barrow and Kendal, Westmoreland, England. 



SPECIES OK THE DEVONIAN 



SPECIES OF THE LOWER HELDERBERG GROUP. 



LYSACTINELLA, Girty. 



1896. LysactiTiella, Girty. Fourteenth Ann. Report N. Y. State Geologist, 

 pp. 258-261, pi. 1. 



This genus has been recently described from free spicules obtained by 

 etching the silica-bearing limestones of the Lower Helderberg grouj) in 

 Albany county, N. Y. Very little is yet known of the form of the sponge 

 body in either of the two species established. Mr. Girty speaks of one 

 species, L. Gehhardi, as being flattened spherical, but of this as probably a 

 quite accidental shape due to compression and distortion. The spicules of 

 this species, so far as isolated, are smooth forms, mostly hexactine and pentac- 

 tine. Lysactinella perelegans is based on a series of spicules Avith echlnate 



