1888.] 



MR. G. H. FOWLER ON A NEW PENNATULA. 



137 



where the two meet. No lateral stripe of siphonozooids is to be 

 found below the lowermost leaves. In transverse section the siphon- 

 ozooids agree with that figured by Hickson (Phil. Trans, vol. 1/4, 

 pi. h. fig. 10), and exhibit a stronu; siphonoglypbe (ciliated groove) 

 at the abaxial end of the stomatodaeum. 



The leaves are placed very obliquely on the rachis, the line of 

 attachment being dorso-ventral. They are approximately triangular 

 in outline, the free sides of the triangle being slightly curved in the 

 usual manner. While the lowermost leaves are placed slightly 

 opposite to each other, those in the middle alternate, and the upper- 

 most are again opposite. There are fourteen pairs of leaves in all, 

 in the sole specimen ; of these only the two lowest are rudimentary, 

 that on the left side being less advanced in development than the 

 corresponding one on the right. All the leaves are much contorted, 

 a result probably dne to death-struggles. 



The uutozooids (fig. 2) are borne on the uppermost (convex) edge. 



Fig. 2. 



Transverse section through an immature autozooid. The leaf is bounded 

 above and below by ectoderm, underneath which lies the thick laver 

 of mesogloea (mesoderm), containing spaces filled by spicules previous 

 to decalcification. The stomatodasura, suspended bv the usual eight 

 mesenteries in the eoelenteron, is lined internally by invaginated ecto- 

 derm, of which the lower (abaxial) tliree fifths are formed of long 

 columnar cells, bearing stout cilia, and constituting a siphonoglj'phe 

 {vide p. 138), X 210. 



and in a well-grown leaf are 2.5-29 in number, arranged in three 

 rows, a median and two lateral. In a less mature leaf, such as that 

 figured, they are fewer in number and form 1-2 rows only. They are 

 4—7 millim'. in length, richly charged with the characteristic spicules, 

 and surmounted by eight strong marginal spines, which may be 2 

 millim. loug. Along the dorsal end of the convex border of the 

 leaf they are continued as a row of immature autozooiJs of varying 

 number, of which the foremost are placed on the rachis, and may 

 even extend to the base of the leaf next above. As has been already 

 stated, they generally meet at an acute angle with the row of siphon- 

 ozooids which runs upwards from the ventral surface between the 

 leaves. 



Proc. Zool. Soc— 1888, No. X. 10 



