320 " ENDEAVOUR " SCIENTIFIC RESULTS. 



branches of about 50 ; each branch springing from an 

 internode of the primary jointed stem, and replacing a 

 hydrocladium. Hydrocladia short, alternate, one on each 

 internode, both series directed towards the front and rising 

 at an angle of about 50 ; nodes transverse or very slightly 

 oblique, often indistinct. 



Hydrothecse at an angle of about 30, deep, very narrow 

 between the median and lateral sarcothecse ; a slight fold 

 or ridge directed obliquely forward near the base, and an 

 extremely fine curved line starting from the top of the lateral 

 sarcotheca and running to the base of the hydrotheca ; border 

 generally with the rudiment of an anterior tooth, sides with 

 minute irregular crenations or sinuations, usually with one 

 slightly larger tooth on each side near the front, back entire, 

 adnate. Hydrothecal internode with very strong divergent 

 septal ridges opposite the intrathecal fold and the base of the 

 lateral sarcothecae, often united by a longitudinal ridge at 

 the back of the internode. 



Mesial sarcotheca about as long as the hydrotheca, very 

 thick, adnate up to the margin, divided into two loculi by 

 an oblique nearly complete septum ; aperture terminal, with 

 a blunt rounded lobe on each side. Lateral sarcothecse wide, 

 reaching the border of the hydrotheca or slightly beyond it, 

 terminal and lateral apertures united. Cauline sarcothecse 

 rather small, two at the base of each hydrocladium. 



Gonangial pinna replacing a hydrocladium, the first inter- 

 node bearing a hydrotheca. Corbula consisting of about 

 seven or eight pairs of leaflets, springing from separate inter- 

 nodes of the rachis as narrow pinnules, but expanding above 

 into wider leaflets, which unite to form a closed corbula ; 

 distal edge of each leaflet with a prominent series of closely- 

 ranked sarcothecse, the rows curved strongly forward ; a 

 short broad lateral process projecting from the distal edge 

 of each leaflet just above its origin, bearing about three 

 sarcothecse, and overlapping the small openings between the 

 bases of the leaflets, the latter marked with linear perisarcal 

 thickenings. 



This remarkable species, so distinct and characteristic alike 

 in its habit and in its minute structure, is in certain points 

 related to the crucialis-group. As in that group its branches 

 and corbulse take the place of hydrocladia, and there is the 

 same tendency to the paired condition, less however in the 

 corbulse than in the branches. The branchlets usually take 

 the place of two successive hydrocladia, so that they are as 

 nearly as possible opposite. The sides of the hydrotheca- 

 border are also very similar to those of A. billardi and A. 



