الفهرس 
Hydroides norvegicaOnly 14 pages are availabe for public view
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Abstract
, histology, hisiiochemistzy a~ad aspects of its ecolosy , - The branchid crown i s composed of t~i~goro ups of -bsn.tacL~s, each consisting of 10-13 biyinnate ten.bacll-es. - There two zltsrnating opercula; one functional and $he other rudhcntary , In the furictioning stag6 t h e operculw i s formed of two crowns one above the other a-nd cach pos ses s ing 13 and 26 soma~tionsr es2ectiv~S;j;. - Intascellulaz spaces appear i n Satih opsrcula and iilcrease iil the rudimentary one, - On functional operculm, eggs fcztilized and ~ertilized were found , t h i s iikiica’css t h a t f=;.z’Gilizatiion may take place on %his structure. - Thorax is foxiied of seven scgmei”zJiis each bears a psi2 of s e r r a t e d setas on e i t h e r side, - Lbd~x~isn bhs l a r g e s t rsgion of bha 53dy c o n s i s t s of 25-60 segments , - The operculaz spines are hollow s-tixc3.wes l i n e d by a thick layei. of cuticle which is of pcsteotive function. - The l~nercr own i s s t r u c t u r a l l y siillila t o t h e upper one cxcept f o r t h e number of blood ondings being fcwer i n the lower one. - T~rGud imenta.ry operculun d i f f e r s fmn t h e f u n c t i o n a l one, t h e fomtr being covsred by 2 t h i n 12yer of c u t i c l e and its l i n i n g spithsliab cclls ax in ail active sfate. - The pinnules are formed of cilia.ted auscous cclls which nag be r~sponsiblsf o r c a t ching food pazticles and directing them b”; t h e i r c i l i a towa.rds the mouth. - The two tenJ~aculzlri p s a r i s e by tha fus ion of t h e tno tentacular gzoupx nearly at the pos*srior t h i r d of thhs branchia.1 C;L’OW~. The illouth opening lies betmeen ths posterior halves of both l i p s . - Thc histology of the body wall shows t h a t its cclls shzrs i n tbe processes of respiratha and tube fomathn, - The coslomic cavi’bies appear i n all pats of the v~om evcn i n the pimules and the two oprrcula, - The alimentary ca.nal is made of four rezions, oesophagus, stoma.ch, intesbine and rectum. - The a n t e r i o r half of the oesophagus is surroundsd by a muscular coat which acts as a sucking pharynx. - The stomach wall is thicker than that of the oesophagus and the c e l l s of t h e a n t e r i o r t h i r d are not c i l i a t e d which suggests Ghat it works as a food storage chamber while the r e s t stands as a digestive rsgion, - The i n t e s t i n e works as a disestive and absorptive rcgion, - The rectum i n short and consists of long ciliated c e l l s which may serve in binding the faeca-l pellets* - gut blood sinus surrounds t h e alimen-bery canal from the hind most segment u n t i l the begining of t h e ossophageal region, Ths dorsal blood vessel appears only i n the a n t e r i o r oesophageal rssion, The v e n t r a l b3 blood vessel is confined t o the thoracic 2nd anterior abdominal region. - The dorsal blood v e s s e l g i v e s rise t o two branchial blood vessels running through the i n t e r n a l cavity of each l i p , The branchial blood vessel of each l i p ramifies inta blind-ending tentaculu branches extending through a11 tsntscles and opercula Into of -l-h% pinnules, the tsntacular blood v e s s e l g i v e s a short pinnulc blood vessel. - Ths nusculax system is eff icier& in the branchial croan, thorax and antcrior region of the abdomen, The great dwslopnent of the longitudinal muscles aSmg the body anables the norm t o withdraw inside the tube. The branchial crown is highly supplied with longitudinal muscle f i b r i l s which are s c a t t e r e d i n the pinnules and Ghc t e n t a c l e s and help the crown i n food capture and g3S cxchang.