178 THE VOYAGE OF H.M.S. CHALLENGER. 
20. Montipora erosa (Dana). 
Manopora erosa, Dana, Zoophytes, p. 504, pl. xlvi. fig. 5. 
The specimen in the collection is much worn, thick and massive. The lobes are much 
less angular than in Dana’s figure; and the cells are twelve-rayed, six being large and 
conspicuous, and the others very small and spinulose. 
Locality.—Mactan Island, Philippines. 
21. Montipora effusa (Dana). 
Manopora effusa, Dana, Zoophytes, p. 500, pl. xlvi. fig. 4. 
The single specimen is a thin and widely explanate, incrusting plate, which is free at 
the margin for a considerable distance. The surface consists of a very open and evenly 
reticulated coenenchyma, becoming denser within. The spinules are rather large, and 
are closely gathered around the cups on all the raised portions of the corallum, becoming 
small and often absent on the concave portions. It seems altogether a rather delicate 
variety of the species. 
Locality.—Samboangan, Philippines. 
22. Montipora aspera, Verrill. 
Manopora ecrista-galli, Dana (non Ehrenberg), Zoophytes, p. 494, pl. xlvi. fig. 1. 
Montipora aspera, Verrill, in Dana, Cor. and Cor. Islands, p. 333. 
This species differs from Montipora crista-galli chiefly in its much more massive 
and uneven growth, the branches being scarcely laminate. The whole corallum is 
rendered extremely rough by the development of numerous angular wings, crests, and 
short, longitudinal rows of papillee, which are very irregularly scattered. The calicles are 
very distinct, rather close between the crests and angular branches, and somewhat indis- 
tinctly and unequally six-rayed ; in many cells a rudimentary second cycle is developed. 
Locality.—Tahiti. 
Family Porrrm2. 
Genus 1. Porites, Lamarck. 
Porites (pars), Lamarck, Hist. Anim. sans Vert., ii. p. 267, 1816. 
», Milne-Edwards and Haime, Cor., iii. p. 173. 
», Duncan, Rey. Madrep., p. 187. 
It has already been shown by Verrill in his description of the Corals of the West 
Coast of America that the presence of two cycles of septa is not always characteristic of 
