191'] Ritter-Forsyth: AscidiaHS of Souihfrn CaUfornia 487 



way of its length ; second, a larger section which makes the loop ; third, 

 a short, very narrow isthmus connecting the large piece just described 

 with rectal limb, the beginning of which is provided with prominent 

 caeca ; and finally, the rectal piece running up left side of body to end 

 as a constricted anus about one-third the distance up branchial sac. 



Postabdomen and reproductive system. — The postabdomen variable 

 in length, often three or four times as long as thorax; about half the 

 diameter of thorax, tapering toward posterior end. The conspicuous 

 cloison, or partition, halves the cavity of postabdomen from right to 

 left ; many round pigment granules occurring in walls of this partition. 

 Numerous regular testis lobes occupy posterior half of postabdomen. 

 The ovary (o., pi. 46, fig. 69) just anterior to the latter, quite remote 

 from intestinal loop. 



Breeding season. — Summer months at least, the atrial chambers of 

 zooids examined at this time being filled with tadpoles. 



Habitat and distribution. — The only localities from which speci- 

 mens have been certainly identified as belonging to A. sotidum are 

 San Diego Bay and Santa ilonica, where they were taken from piles 

 in both localities. Almost certainly, however, the species occurs in 

 Monterey Bay and other northerly points. 



Type locality. — San Diego Bay. 



The great variability in the colonies of A. californicum makes the 

 species seem to include solid^im so far as external appearance is con- 

 cerned, and since the two overlap a good deal in distribution, if indeed 

 they are not coincident, the collector is likely to confuse them at times. 

 In general, however, the much greater massiveness of solidum will 

 distinguish them even to cursory observation. But examination of the 

 zooids leaves no question about the specific distinctness of the two. 

 Perhaps the most accessible point of distinction between the zooids of 

 the two is in the secondary lobing of the lobes of the branchial siphon 

 of A. solidum and the teeth around the atrial orifice in the same 

 species. 



A. solidum ha.s much in common with A. obesum Sluit. (Sluiter, 

 1900) from the Chatham Islands. But the two are well distinguished, 

 seemingly, by a number of characteristics, notably the undivided 

 branchial lobes and the absence of denticles around the atrial orifice 

 in obesum. In fact, the two positive characteristics in solidum are 

 very exceptional in the genus Amaroucium. 



Amaroucium aequali-siphonis, n. sp. 



PI. ,38, fig. 4; pi. 4.5, fig. 61 



Superficial characteristics of the colony. — Consisting of long, 

 pedunculated, club-shaped lobes, completely encrusted with sand, each 

 growing from a basal network. Both head and peduncle of each lobe 



