32 CCELENTERATA. 



TUBULARIA. (Parypha.) 



This form is frequently abundant on the piles of old wharfs 

 and on rocks, where the colored colonies form conspicuous masses 

 just below low-water mark. 



Examine the general form of a colony and note, either with 

 a hand lens or with the naked eye, the stem, or hydrocaulus, as 

 it arises from the branching, matted hydrorhizal portion of the 

 colony. The parts of the colony will be seen to differ from the 

 Leptomedusan (Campanularian) form studied, especially in 

 branching, rigidity, hydrotheca3, and gonosomes. 



Make a drawing to show the formation of the colony. 



1. How does a hydranth differ from the hydranth of Obelia 

 in the matter of tentacles? Is a hydrotheca present? 



2. The mouth is terminal and is situated at the end of a 

 proboscis. 



3. The short but rather large body of the hydranth passes 

 back to the perisarc as the fleshy axis, ccenosarc. 



4. Notice the gonosomes between the rows of tentacles. 

 What is their origin and arrangement? This is a form in which 

 the medusae are not set free, but remain vestigial. They show 

 neither radiating nor circular canals. The gonads ripen on the 

 partially developed manubrium of the medusa. The sexes are 

 separate. 



Make a drawing of a hydranth. 



5. The male gonophores when nearly mature are rounded or 

 elongated with the space apparently between the manubrium 

 and sub-umbrellar surface filled with sperm. In fact, the sperm 

 are enclosed between the ectoderm and endoderm of the 

 manubrium, but the ectoderm is pressed over against the ecto- 

 derm of the sub-umbrella so this space is practically obliterated. 

 These sperm become active when liberated in sea-water. 



6. The female gonophore when mature is more elongated, 

 shows indications of tentacles at the free extremity, and there is 

 an actual sub-umbrellar space. The eggs are formed in the 

 ectoderm of the manubrium, are shed into the sub-umbrellar 

 cavity, and develop into actinulce. With needles open a female 



