HOTItYLLUS. 



53 



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IG. 115. Structure of Botryllida). " Botryllus stellatus" Renier in 

 'Opusc. scelti Scienze.'xvi (1793), pi. i; Polycyclus Renieri Lamarck 

 in ' Mom. du Mas.' I (1815), p. 340. 1. A colony adhering- to two 

 fronds of Zostera, natural size. 2. A system, enlarged, a, branchial 

 apertures; b, common excretory orifice; e, individuals. 3. Part 

 of the same, viewed from above, b, common excretory orifice; 

 d, branchial aperture. 4. A portion of the net-like bottom of b, 

 fi.i, f . 3, further enlarged. 5. Transverse section of the colony, natural 

 size. (i. Part of the same, enlarged. 7. Section of a system, 

 enlarged, n, branchial apertures ; c, common excretory canal ; (?, 

 atrial apertiires ; e, individuals. 8. A single individual, further 

 enlarged. 9. The same, natural size. 10. Part of the tnnic (as 

 seen in fig. 8), much enlarged. 11. A portion of the same, seen in 

 profile, further enlarged. 12. Part of the common envelope, much 

 enlarged, showing (probably) germs secreted in it. 13. An Asci<H, 

 about natural size, introduced for comparison. 



