BULLETIN oi), UNITED STATES NATIONAL MUSEUM. lill 



ular, with a ring of sei>tal granules, jui^t tletacheil from the wall in the tliin-walled calicU'S. In the 

 thiik-walleil oalicles the septa are more regular, theseiital granules are on the edges of tlie wall, ami the 

 septa themselves fuse in the four primipal pairs. The pah are ro<l-like, hut appear as small, incon- 

 spicuous granules. The full foruuila can be usually seen, the lateral members of the ventral triplet 

 being variable. A ragged columellar tulx-rcle is usually present. The interseptal loculi are large and 

 deep, but not sharply outlined, owing to the slight frosting of the sides of the sei)ta. The calicles on 

 the flat tops o]ien in a spongy stroma, and are consjiicuous from the large size of the columellar tangle, 

 surrounded by rings of ojx'n inter-si'ptal loculi. 



In sections of the stems the trabeeulie are well developed, but not crowded. 



This coral is describeil by Air. (.Juelch as being e;isily distinguished from the " I'orites monlax" of 

 Dana from the same locality. The growth form is different and the living layer is much less e.'sten- 

 sive. But there is evidently a strong family likeness between all of these Sandwich Islands forms. 

 The calicles of this type, at least where the walls are thin, are very like those of Poritex Sauduiih 

 Ishmih (i and 7, yet all differ in finer structural details. X strong family likeness between corals from 

 the same locality has been frequently noticed in these catalogues. 



It is worth noting that while the calicles opening in the stroma on the tops of the -stems are sepa- 

 rated liy thick reticular walls those which are fully formed and ranged at the sides of the stem have 

 their walls thin and sharp; when these again thicken and become reticular the reticulum is more 

 rigid and seems here and there to show slight traces of its formation out of an inner synapticular wall, 

 although the retii'uluui in thickening stems would usually be due to the appearance of intervening 

 tissue. 



This is one.of the few Indo- Pacific Pontes which show some approach to the characteristic method 

 of branching seen in the West Indian forms. 



REMARK.'^ OX THE INTERRELATION OF THE FORM.E OF PORITES COMPRESSA. 



The fornise that exhibit the characteri.stics of the specie.s in their lea.st inoditicd 

 condition are conjinujens and ahacus. The caliciilar characters in these two arc prac- 

 tically identical: there is .sonie difference in form, and they respectively lead to 

 divergent variations. Forma I'hmgata, however, might as easily be derived fiDiii 

 co>iji/7i(/e)is with separate branches as from ahacu.s; and forma fumiiJa miffht be con- 

 sidered conjungenx with abbreviated branches, swollen below their ends. 



Forma conjungens leads into forma (nH/nxtliiepta and forma profitndicahjie. The 

 septal and palar formula" in these three are the same, the differences consistin<j in 

 the relati\'e development of the septiil trranules and the outer synapticular riti<>-. 

 In some calices of cotijumji-nx the outer synapticular rino- is not complete, and the 

 wall tall; if the septal granules are rather prominent, the characters of cuigust!- 

 septa are reproduced; if the septal granules are reduced in size, tho.se of profini<h'- 

 caly.r are presented. These three forma' interlock each with the other. l)ut there ate 

 clearly recognizable average ditfereni'es between the sjjecimtMis. 



Forma (inguntixepta has two subforms that differ in minor characters from the 

 t\'pical sj)ecimens. Forma ihliaiinJit has delicate pali and very delicately iind 

 thickly frosted skeletal surfaces; subforma jKnicixjiind has sharper and more scat- 

 tered septal granulations and a generally more ragged appeanince of the skeletal 

 parts. These ditl'erences are so very slight that it is doiibtt'ul if they are of more than 

 individual importance. 



Forma. _frag His uiaj' possibly represent ii separate species, but as it presents all 

 the fundamental structural chiiiacters of foriiui diujuxflx, ptii. differing chiefly by its 

 thinner skeletal parts, more delicate pali. and more delicate surface frostings, it 

 probabh' belongs in the series. 



