28 



THE HYDRO MEDUSAE 



gonotheca, sccated upon a peduncle continuous with the opercular 

 plato. This type of goiiophorc has ])een termed a wccowidinm. 



2. In Calycella lacerata a blastostyle and gonophore at first lie 

 inside a gonotheca of the usual type; the gonophore when nearly 

 mature migrates up the blastostyle, and i)rojccting beyond the 

 mouth of the gonotheca, secretes a spherical gelatinous cyst, the 

 acrocyst, in which it completes the maturation of the generative 

 colls. In Sertularia pumila the gonophore, having formed the 

 acrocyst as above described, withdraws again into the gonangium, 

 leaving the ova behind to develop (Fig. ^^0). 



Fid. 8:i 



Fli!. Si'i, 



Fio. 37. 



3,'). - noiiotlu'ca t)f ( ibi'lia. Kroni tlir criiinil MiiNtONtylc lire bixhU'tl iiuiuerouN ^onophores, 

 oncli of wlilcli I H'f. 11 lies 11 fr swiiiiiiiiiin liicduHdiil. (AttiT Alllimii.) 



ail.- DiiiKi-iiiiiiimtio si'otiiJii of tin- n<'i"iI'lior.« of Srrlulitria pumila. A, tho norocyst, con- 

 titiiiiiiK ovii ; H, coi'li'iiti'ion of tli« liln.sto.stylo ; (.', tlio llrst n'l'iopl'ort' (Hporosiu-), whicli ImN 

 foniii'cl, 1111(1 ivtircil from, tlii» ncrocytit, coniu't-tiMl witli tlio iierisiirc on tli<< li-ll bv .stniiul.s of 

 ti.sHiui (nulMTimiMilii); '<"J, tliH sflcoiul K'>iioiihoiv iil iin .'iiily sUini- of foriimtiou oiitlio blii.slo- 

 Htyln ; (*/', oiMTciiliir |iliit.', an oxpiiiision at llio ilisUl I'liil of tho Ilist KWiophore ; V, in'risarc of 

 thii KoiioUim-a. (AltiT WfiNiiiiiiin.) 



3'. — I'hylai-tociirii (i'(irlinla) vf Aiil(ioi>hfnla attenvata, sido vl<>w. At tlio point of origin of 

 tho iiliyliictoourp from thn liydrocliKliuni is n hy(lrothi>pn with tho nmml throo nt'mHtoi.hon>K ; 

 tho phylactoonrp itMolf ih compoHoil of rilw cnrryln^ nniiioroiiH nomntoplioros ; tho ri lis tl>;nn'(l 

 nivli ov.T to moot thoKO of tho othor side, and covor tho Konoidioros (not shown in tlio llgurc). 

 (Aftor Allnian.) 



3. In Sertularia rosacea, in which the gonophore is also 

 borne on a bliisto.stylo, the oj)ercular jilate sends out eight hollow 

 arms, con.si.sting of the usual body layers; these, projecting out- 

 wards beyond the mouth of the gonotheca, secrete eight Hat spines 

 which bond inwards to servo as a luarsupium for tho reception and 

 protection of the acrocyst. 



4. Another method of protection for tho gonophore is found 



II 



