Fam. I. Doliopsidae. Atria and protostigmata entirely behind endostyle. Ciliated spire behind the brain. Somatic muscles not forming loops. Stolon extended on to dorsal outgrowth. Blasto zooids globose, arranged on the outgrowth in groups, not rows. Doliopsis, Vogt (= Anchinia, Esch.). (Oozooid known only by fragments of dorsal outgrowth.) Phorozooids and gonozooids with a praeoral and a supracloacal tentacle, lacking in the tropho zooids. Somatic muscles a pair of S-shaped strands.
Fam. II. Doliolidae. Oozooid and locomotive buds barrel shaped, the former with 9, the latter with 8, muscular hoops. Oozooid with an otocyst on the left side, and 4 longitudinal rows of buds on its dorsal process—trophozooids along the sides, phorozooids down the middle, the latter carrying gonozooid buds on their stalks of attachment. Trophozooids with gaping mouth and half-obliterated cloaca. Phorozooid and gonozooid without supra-cloacal outgrowth or otocyst. Ciliated spire before the brain. Stolon short ; buds all migratory.
Doliolina, Borgert. All protostigmata ( < 5o) in a transverse series behind endostyle. Intestine U-shaped, e.g., D. mfilleri, D. krohni (with 3 pairs of lateral vascular appendages). Dolio lum, Q. and G. with antero-dorsal atrial extensions in gonozooid, carrying numerous additional protostigmata. Intestine directed backwards or twisted to right, e.g., D. denticulatum.
Suborder 3. SALPIDA ( =Desmomyaria) Oozooid (solitary form, or nurse) asexual, free-swimming and bud ding freely, in general resembling the blastozooids, but tending to greater size (often twice as large) and muscularity. Blastozooids all locomotive and hermaphrodite. Cloaca dorsal, atriopore pos terodorsal, separated from pharynx by an oblique median vascular tract (the gill), with transverse ciliated stripes and an elongated gap on either side. Muscles as transverse bands often connected dorsally (i.e., Desmomyarian), usually incomplete ventrally (i.e., Hemimyarian), with a tendency to polymerisation and elongation of cloacal siphon in oozooid. Oesophagus ventral. Gut a sinistral loop, protruding as a postero-ventral hernia, or compressed into a compact "nucleus." A cerebral eye, but no otocyst. No typical neural (hypophysial) gland, but a detached ciliated pit in front, and below the brain a pair of peculiar pharyngeal diverticula (extra-neural glands), unpaired in Thetys, rarely absent (Thalia).
Stolon long. Buds at first vertical in a linear series; then in two alternating rows with atriopores outwards ; finally adher ing to one another merely by papillae (usually 8). Portions de tached at intervals as free colonies, usually in chains, rarely wheels (aggregated or chain forms), certain features of the blasto zooids being related to this phase (asymmetry of right- and left sided individuals, elevation and forward rotation of eye, adhesive organs, etc.). Ultimately the blastozooids become free and give rise to embryos (usually i each) with placental development.
Pending corfipletion of certain investigations on the endostyle (Garstang and Platt, 1928), some results of which are here embodied, the following attempt at a phyletic grouping of the various forms is provisional. Metcalf's sub-genera (1918) are adopted as natural groups of species, though the homogeneity of the Ritteriella group is not above question. In R. amboinensis the marginal bands of the endostyle are asymmetrical.
Abbreviations.—M = Muscles, OZ=Oozooid, BZ = Blastozo oid. The fractions represent the number of conspicuous muscle bands in — omitting those of the siphons. Unless otherwise BZ' stated the muscles are complete dorsally and incomplete ventrally, and the embryos are single on the right cloacal wall.